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nixpkgs/pkgs/os-specific/linux/kernel/patch-2.6.21-ck1

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Index: linux-2.6.21-ck1/Makefile
===================================================================
--- linux-2.6.21-ck1.orig/Makefile 2007-05-04 12:10:52.000000000 +1000
+++ linux-2.6.21-ck1/Makefile 2007-05-04 12:21:37.000000000 +1000
@@ -1,7 +1,7 @@
VERSION = 2
PATCHLEVEL = 6
SUBLEVEL = 21
-EXTRAVERSION =
+EXTRAVERSION = -ck1
NAME = Nocturnal Monster Puppy
# *DOCUMENTATION*
Index: linux-2.6.21-ck1/kernel/workqueue.c
===================================================================
--- linux-2.6.21-ck1.orig/kernel/workqueue.c 2007-05-04 12:10:52.000000000 +1000
+++ linux-2.6.21-ck1/kernel/workqueue.c 2007-05-04 12:10:54.000000000 +1000
@@ -355,8 +355,6 @@ static int worker_thread(void *__cwq)
if (!cwq->freezeable)
current->flags |= PF_NOFREEZE;
- set_user_nice(current, -5);
-
/* Block and flush all signals */
sigfillset(&blocked);
sigprocmask(SIG_BLOCK, &blocked, NULL);
Index: linux-2.6.21-ck1/fs/proc/array.c
===================================================================
--- linux-2.6.21-ck1.orig/fs/proc/array.c 2007-05-04 12:10:52.000000000 +1000
+++ linux-2.6.21-ck1/fs/proc/array.c 2007-05-04 12:10:54.000000000 +1000
@@ -165,7 +165,6 @@ static inline char * task_state(struct t
rcu_read_lock();
buffer += sprintf(buffer,
"State:\t%s\n"
- "SleepAVG:\t%lu%%\n"
"Tgid:\t%d\n"
"Pid:\t%d\n"
"PPid:\t%d\n"
@@ -173,7 +172,6 @@ static inline char * task_state(struct t
"Uid:\t%d\t%d\t%d\t%d\n"
"Gid:\t%d\t%d\t%d\t%d\n",
get_task_state(p),
- (p->sleep_avg/1024)*100/(1020000000/1024),
p->tgid, p->pid,
pid_alive(p) ? rcu_dereference(p->real_parent)->tgid : 0,
pid_alive(p) && p->ptrace ? rcu_dereference(p->parent)->pid : 0,
Index: linux-2.6.21-ck1/include/linux/init_task.h
===================================================================
--- linux-2.6.21-ck1.orig/include/linux/init_task.h 2007-05-04 12:10:52.000000000 +1000
+++ linux-2.6.21-ck1/include/linux/init_task.h 2007-05-04 12:24:19.000000000 +1000
@@ -102,13 +102,15 @@ extern struct group_info init_groups;
.prio = MAX_PRIO-20, \
.static_prio = MAX_PRIO-20, \
.normal_prio = MAX_PRIO-20, \
+ .rotation = 0, \
.policy = SCHED_NORMAL, \
.cpus_allowed = CPU_MASK_ALL, \
.mm = NULL, \
.active_mm = &init_mm, \
.run_list = LIST_HEAD_INIT(tsk.run_list), \
.ioprio = 0, \
- .time_slice = HZ, \
+ .time_slice = 1000000000, \
+ .quota = 1000000000, \
.tasks = LIST_HEAD_INIT(tsk.tasks), \
.ptrace_children= LIST_HEAD_INIT(tsk.ptrace_children), \
.ptrace_list = LIST_HEAD_INIT(tsk.ptrace_list), \
@@ -135,6 +137,7 @@ extern struct group_info init_groups;
.signal = {{0}}}, \
.blocked = {{0}}, \
.alloc_lock = __SPIN_LOCK_UNLOCKED(tsk.alloc_lock), \
+ .mutexes_held = 0, \
.journal_info = NULL, \
.cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \
.fs_excl = ATOMIC_INIT(0), \
Index: linux-2.6.21-ck1/include/linux/sched.h
===================================================================
--- linux-2.6.21-ck1.orig/include/linux/sched.h 2007-05-04 12:10:52.000000000 +1000
+++ linux-2.6.21-ck1/include/linux/sched.h 2007-05-04 12:24:19.000000000 +1000
@@ -34,9 +34,14 @@
#define SCHED_FIFO 1
#define SCHED_RR 2
#define SCHED_BATCH 3
+#define SCHED_ISO 4
+#define SCHED_IDLEPRIO 5
#ifdef __KERNEL__
+#define SCHED_MAX SCHED_IDLEPRIO
+#define SCHED_RANGE(policy) ((policy) <= SCHED_MAX)
+
struct sched_param {
int sched_priority;
};
@@ -149,8 +154,7 @@ extern unsigned long weighted_cpuload(co
#define EXIT_ZOMBIE 16
#define EXIT_DEAD 32
/* in tsk->state again */
-#define TASK_NONINTERACTIVE 64
-#define TASK_DEAD 128
+#define TASK_DEAD 64
#define __set_task_state(tsk, state_value) \
do { (tsk)->state = (state_value); } while (0)
@@ -522,14 +526,19 @@ struct signal_struct {
#define MAX_USER_RT_PRIO 100
#define MAX_RT_PRIO MAX_USER_RT_PRIO
+#define PRIO_RANGE (40)
+#define ISO_PRIO (MAX_RT_PRIO - 1)
-#define MAX_PRIO (MAX_RT_PRIO + 40)
+#define MAX_PRIO (MAX_RT_PRIO + PRIO_RANGE)
-#define rt_prio(prio) unlikely((prio) < MAX_RT_PRIO)
+#define rt_prio(prio) unlikely((prio) < ISO_PRIO)
#define rt_task(p) rt_prio((p)->prio)
#define batch_task(p) (unlikely((p)->policy == SCHED_BATCH))
-#define is_rt_policy(p) ((p) != SCHED_NORMAL && (p) != SCHED_BATCH)
+#define is_rt_policy(policy) ((policy) == SCHED_FIFO || \
+ (policy) == SCHED_RR)
#define has_rt_policy(p) unlikely(is_rt_policy((p)->policy))
+#define iso_task(p) unlikely((p)->policy == SCHED_ISO)
+#define idleprio_task(p) unlikely((p)->policy == SCHED_IDLEPRIO)
/*
* Some day this will be a full-fledged user tracking system..
@@ -740,6 +749,22 @@ extern unsigned int max_cache_size;
#endif /* CONFIG_SMP */
+/*
+ * A runqueue laden with a single nice 0 task scores a weighted_cpuload of
+ * SCHED_LOAD_SCALE. This function returns 1 if any cpu is laden with a
+ * task of nice 0 or enough lower priority tasks to bring up the
+ * weighted_cpuload
+ */
+static inline int above_background_load(void)
+{
+ unsigned long cpu;
+
+ for_each_online_cpu(cpu) {
+ if (weighted_cpuload(cpu) >= SCHED_LOAD_SCALE)
+ return 1;
+ }
+ return 0;
+}
struct io_context; /* See blkdev.h */
struct cpuset;
@@ -788,13 +813,6 @@ struct mempolicy;
struct pipe_inode_info;
struct uts_namespace;
-enum sleep_type {
- SLEEP_NORMAL,
- SLEEP_NONINTERACTIVE,
- SLEEP_INTERACTIVE,
- SLEEP_INTERRUPTED,
-};
-
struct prio_array;
struct task_struct {
@@ -814,20 +832,33 @@ struct task_struct {
int load_weight; /* for niceness load balancing purposes */
int prio, static_prio, normal_prio;
struct list_head run_list;
+ /*
+ * This bitmap shows what priorities this task has received quota
+ * from for this major priority rotation on its current runqueue.
+ */
+ DECLARE_BITMAP(bitmap, PRIO_RANGE + 1);
struct prio_array *array;
+ /* Which major runqueue rotation did this task run */
+ unsigned long rotation;
unsigned short ioprio;
#ifdef CONFIG_BLK_DEV_IO_TRACE
unsigned int btrace_seq;
#endif
- unsigned long sleep_avg;
unsigned long long timestamp, last_ran;
unsigned long long sched_time; /* sched_clock time spent running */
- enum sleep_type sleep_type;
unsigned long policy;
cpumask_t cpus_allowed;
- unsigned int time_slice, first_time_slice;
+ /*
+ * How much this task is entitled to run at the current priority
+ * before being requeued at a lower priority.
+ */
+ int time_slice;
+ /* Is this the very first time_slice this task has ever run. */
+ unsigned int first_time_slice;
+ /* How much this task receives at each priority level */
+ int quota;
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
struct sched_info sched_info;
@@ -992,6 +1023,7 @@ struct task_struct {
struct held_lock held_locks[MAX_LOCK_DEPTH];
unsigned int lockdep_recursion;
#endif
+ unsigned long mutexes_held;
/* journalling filesystem info */
void *journal_info;
@@ -1156,8 +1188,10 @@ static inline void put_task_struct(struc
#define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */
#define PF_SPREAD_PAGE 0x01000000 /* Spread page cache over cpuset */
#define PF_SPREAD_SLAB 0x02000000 /* Spread some slab caches over cpuset */
+#define PF_ISOREF 0x04000000 /* SCHED_ISO task has used up quota */
#define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */
#define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */
+#define PF_NONSLEEP 0x40000000 /* Waiting on in-kernel activity */
/*
* Only the _current_ task can read/write to tsk->flags, but other
Index: linux-2.6.21-ck1/kernel/sched.c
===================================================================
--- linux-2.6.21-ck1.orig/kernel/sched.c 2007-05-04 12:10:52.000000000 +1000
+++ linux-2.6.21-ck1/kernel/sched.c 2007-05-04 12:24:22.000000000 +1000
@@ -16,6 +16,7 @@
* by Davide Libenzi, preemptible kernel bits by Robert Love.
* 2003-09-03 Interactivity tuning by Con Kolivas.
* 2004-04-02 Scheduler domains code by Nick Piggin
+ * 2007-03-02 Staircase deadline scheduling policy by Con Kolivas
*/
#include <linux/mm.h>
@@ -52,6 +53,7 @@
#include <linux/tsacct_kern.h>
#include <linux/kprobes.h>
#include <linux/delayacct.h>
+#include <linux/log2.h>
#include <asm/tlb.h>
#include <asm/unistd.h>
@@ -83,126 +85,85 @@ unsigned long long __attribute__((weak))
#define USER_PRIO(p) ((p)-MAX_RT_PRIO)
#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
+#define SCHED_PRIO(p) ((p)+MAX_RT_PRIO)
-/*
- * Some helpers for converting nanosecond timing to jiffy resolution
- */
-#define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
+/* Some helpers for converting to/from various scales.*/
#define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
-
-/*
- * These are the 'tuning knobs' of the scheduler:
- *
- * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
- * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
- * Timeslices get refilled after they expire.
- */
-#define MIN_TIMESLICE max(5 * HZ / 1000, 1)
-#define DEF_TIMESLICE (100 * HZ / 1000)
-#define ON_RUNQUEUE_WEIGHT 30
-#define CHILD_PENALTY 95
-#define PARENT_PENALTY 100
-#define EXIT_WEIGHT 3
-#define PRIO_BONUS_RATIO 25
-#define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
-#define INTERACTIVE_DELTA 2
-#define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
-#define STARVATION_LIMIT (MAX_SLEEP_AVG)
-#define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
-
-/*
- * If a task is 'interactive' then we reinsert it in the active
- * array after it has expired its current timeslice. (it will not
- * continue to run immediately, it will still roundrobin with
- * other interactive tasks.)
- *
- * This part scales the interactivity limit depending on niceness.
- *
- * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
- * Here are a few examples of different nice levels:
- *
- * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
- * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
- * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
- * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
- * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
- *
- * (the X axis represents the possible -5 ... 0 ... +5 dynamic
- * priority range a task can explore, a value of '1' means the
- * task is rated interactive.)
- *
- * Ie. nice +19 tasks can never get 'interactive' enough to be
- * reinserted into the active array. And only heavily CPU-hog nice -20
- * tasks will be expired. Default nice 0 tasks are somewhere between,
- * it takes some effort for them to get interactive, but it's not
- * too hard.
- */
-
-#define CURRENT_BONUS(p) \
- (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
- MAX_SLEEP_AVG)
-
-#define GRANULARITY (10 * HZ / 1000 ? : 1)
-
-#ifdef CONFIG_SMP
-#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
- (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
- num_online_cpus())
-#else
-#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
- (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
-#endif
-
-#define SCALE(v1,v1_max,v2_max) \
- (v1) * (v2_max) / (v1_max)
-
-#define DELTA(p) \
- (SCALE(TASK_NICE(p) + 20, 40, MAX_BONUS) - 20 * MAX_BONUS / 40 + \
- INTERACTIVE_DELTA)
-
-#define TASK_INTERACTIVE(p) \
- ((p)->prio <= (p)->static_prio - DELTA(p))
-
-#define INTERACTIVE_SLEEP(p) \
- (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
- (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
-
-#define TASK_PREEMPTS_CURR(p, rq) \
- ((p)->prio < (rq)->curr->prio)
-
-#define SCALE_PRIO(x, prio) \
- max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
-
-static unsigned int static_prio_timeslice(int static_prio)
-{
- if (static_prio < NICE_TO_PRIO(0))
- return SCALE_PRIO(DEF_TIMESLICE * 4, static_prio);
- else
- return SCALE_PRIO(DEF_TIMESLICE, static_prio);
-}
-
-/*
- * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
- * to time slice values: [800ms ... 100ms ... 5ms]
- *
- * The higher a thread's priority, the bigger timeslices
- * it gets during one round of execution. But even the lowest
- * priority thread gets MIN_TIMESLICE worth of execution time.
+#define MS_TO_NS(TIME) ((TIME) * 1000000)
+#define MS_TO_US(TIME) ((TIME) * 1000)
+#define US_TO_MS(TIME) ((TIME) / 1000)
+
+#define TASK_PREEMPTS_CURR(p, curr) ((p)->prio < (curr)->prio)
+
+/*
+ * This is the time all tasks within the same priority round robin.
+ * Value is in ms and set to a minimum of 8ms. Scales with number of cpus.
+ * Tunable via /proc interface.
+ */
+int rr_interval __read_mostly = 6;
+int sched_interactive __read_mostly = 1;
+
+/*
+ * sched_iso_cpu - sysctl which determines the cpu percentage SCHED_ISO tasks
+ * are allowed to run (over ISO_PERIOD seconds) as real time tasks.
+ * sched_iso_period - sysctl which determines the number of seconds over
+ * which cpu usage of SCHED_ISO tasks is averaged to determine if they are
+ * exceeding their allowable bandwidth.
+*/
+int sched_iso_cpu __read_mostly = 80;
+int sched_iso_period __read_mostly = 5;
+
+#define ISO_PERIOD ((sched_iso_period * HZ) + 1)
+
+/*
+ * This contains a bitmap for each dynamic priority level with empty slots
+ * for the valid priorities each different nice level can have. It allows
+ * us to stagger the slots where differing priorities run in a way that
+ * keeps latency differences between different nice levels at a minimum.
+ * The purpose of a pre-generated matrix is for rapid lookup of next slot in
+ * O(1) time without having to recalculate every time priority gets demoted.
+ * All nice levels use priority slot 39 as this allows less niced tasks to
+ * get all priority slots better than that before expiration is forced.
+ * ie, where 0 means a slot for that priority, priority running from left to
+ * right is from prio 0 to prio 39:
+ * nice -20 0000000000000000000000000000000000000000
+ * nice -10 1000100010001000100010001000100010010000
+ * nice 0 1010101010101010101010101010101010101010
+ * nice 5 1011010110110101101101011011010110110110
+ * nice 10 1110111011101110111011101110111011101110
+ * nice 15 1111111011111110111111101111111011111110
+ * nice 19 1111111111111111111111111111111111111110
*/
+static unsigned long prio_matrix[PRIO_RANGE][BITS_TO_LONGS(PRIO_RANGE)]
+ __read_mostly;
-static inline unsigned int task_timeslice(struct task_struct *p)
-{
- return static_prio_timeslice(p->static_prio);
-}
+struct rq;
/*
* These are the runqueue data structures:
*/
-
struct prio_array {
- unsigned int nr_active;
- DECLARE_BITMAP(bitmap, MAX_PRIO+1); /* include 1 bit for delimiter */
- struct list_head queue[MAX_PRIO];
+ /* Tasks queued at each priority */
+ struct list_head queue[MAX_PRIO + 1];
+
+ /*
+ * The bitmap of priorities queued for this array. While the expired
+ * array will never have realtime tasks on it, it is simpler to have
+ * equal sized bitmaps for a cheap array swap. Include 1 bit for
+ * delimiter.
+ */
+ DECLARE_BITMAP(prio_bitmap, MAX_PRIO + 1);
+
+ /*
+ * The best static priority (of the dynamic priority tasks) queued
+ * this array.
+ */
+ int best_static_prio;
+
+#ifdef CONFIG_SMP
+ /* For convenience looks back at rq */
+ struct rq *rq;
+#endif
};
/*
@@ -234,14 +195,28 @@ struct rq {
*/
unsigned long nr_uninterruptible;
- unsigned long expired_timestamp;
/* Cached timestamp set by update_cpu_clock() */
unsigned long long most_recent_timestamp;
struct task_struct *curr, *idle;
unsigned long next_balance;
struct mm_struct *prev_mm;
- struct prio_array *active, *expired, arrays[2];
- int best_expired_prio;
+
+ struct prio_array *active, *expired, *idleprio, arrays[2];
+ unsigned long *dyn_bitmap, *exp_bitmap;
+
+ /*
+ * The current dynamic priority level this runqueue is at per static
+ * priority level.
+ */
+ int prio_level[PRIO_RANGE];
+
+ /* How many times we have rotated the priority queue */
+ unsigned long prio_rotation;
+ unsigned long iso_ticks;
+ unsigned short iso_refractory;
+
+ /* Number of idleprio tasks running */
+ unsigned long nr_idleprio;
atomic_t nr_iowait;
#ifdef CONFIG_SMP
@@ -579,12 +554,9 @@ static inline struct rq *this_rq_lock(vo
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
/*
* Called when a process is dequeued from the active array and given
- * the cpu. We should note that with the exception of interactive
- * tasks, the expired queue will become the active queue after the active
- * queue is empty, without explicitly dequeuing and requeuing tasks in the
- * expired queue. (Interactive tasks may be requeued directly to the
- * active queue, thus delaying tasks in the expired queue from running;
- * see scheduler_tick()).
+ * the cpu. We should note that the expired queue will become the active
+ * queue after the active queue is empty, without explicitly dequeuing and
+ * requeuing tasks in the expired queue.
*
* This function is only called from sched_info_arrive(), rather than
* dequeue_task(). Even though a task may be queued and dequeued multiple
@@ -682,71 +654,304 @@ sched_info_switch(struct task_struct *pr
#define sched_info_switch(t, next) do { } while (0)
#endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */
+static int idleprio_suitable(struct task_struct *p)
+{
+ return (!p->mutexes_held && !freezing(p) && !signal_pending(p) &&
+ !(p->flags & (PF_NONSLEEP | PF_EXITING)));
+}
+
+static int idleprio(const struct task_struct *p)
+{
+ return (p->prio == MAX_PRIO);
+}
+
+static inline int task_queued(struct task_struct *task)
+{
+ return !list_empty(&task->run_list);
+}
+
+static inline void set_dynamic_bit(struct task_struct *p, struct rq *rq)
+{
+ __set_bit(p->prio, p->array->prio_bitmap);
+}
+
/*
- * Adding/removing a task to/from a priority array:
+ * Removing from a runqueue.
*/
-static void dequeue_task(struct task_struct *p, struct prio_array *array)
+static void dequeue_task(struct task_struct *p, struct rq *rq)
{
- array->nr_active--;
- list_del(&p->run_list);
- if (list_empty(array->queue + p->prio))
- __clear_bit(p->prio, array->bitmap);
+ list_del_init(&p->run_list);
+ if (idleprio_task(p) && idleprio(p))
+ rq->nr_idleprio--;
+ else if (list_empty(p->array->queue + p->prio))
+ __clear_bit(p->prio, p->array->prio_bitmap);
}
-static void enqueue_task(struct task_struct *p, struct prio_array *array)
+static void reset_first_time_slice(struct task_struct *p)
{
- sched_info_queued(p);
- list_add_tail(&p->run_list, array->queue + p->prio);
- __set_bit(p->prio, array->bitmap);
- array->nr_active++;
+ if (unlikely(p->first_time_slice))
+ p->first_time_slice = 0;
+}
+
+/*
+ * The task is being queued on a fresh array so it has its entitlement
+ * bitmap cleared.
+ */
+static void task_new_array(struct task_struct *p, struct rq *rq,
+ struct prio_array *array)
+{
+ bitmap_zero(p->bitmap, PRIO_RANGE);
+ p->rotation = rq->prio_rotation;
+ p->time_slice = p->quota;
p->array = array;
+ reset_first_time_slice(p);
+}
+
+/* Find the first slot from the relevant prio_matrix entry */
+static int first_prio_slot(struct task_struct *p)
+{
+ if (unlikely(p->policy == SCHED_BATCH))
+ return p->static_prio;
+ return SCHED_PRIO(find_first_zero_bit(
+ prio_matrix[USER_PRIO(p->static_prio)], PRIO_RANGE));
}
/*
- * Put task to the end of the run list without the overhead of dequeue
- * followed by enqueue.
+ * In sched_interactive mode priority allocation occurs per process per rq
+ * array swap. In !sched_interactive mode all waking tasks must obey the
+ * current prio level of all other tasks running per array swap.
*/
-static void requeue_task(struct task_struct *p, struct prio_array *array)
+static int minprio(struct rq *rq, int uprio)
{
- list_move_tail(&p->run_list, array->queue + p->prio);
+ if (sched_interactive)
+ return MAX_RT_PRIO;
+ return rq->prio_level[uprio];
}
-static inline void
-enqueue_task_head(struct task_struct *p, struct prio_array *array)
+/*
+ * Find the first unused slot by this task that is also in its prio_matrix
+ * level. SCHED_BATCH tasks do not use the priority matrix. They only take
+ * priority slots from their static_prio and above.
+ */
+static int next_entitled_slot(struct task_struct *p, struct rq *rq)
{
- list_add(&p->run_list, array->queue + p->prio);
- __set_bit(p->prio, array->bitmap);
- array->nr_active++;
- p->array = array;
+ int search_prio = MAX_RT_PRIO, uprio = USER_PRIO(p->static_prio);
+ struct prio_array *array = rq->active;
+ DECLARE_BITMAP(tmp, PRIO_RANGE);
+
+ /*
+ * Go straight to expiration if there are higher priority tasks
+ * already expired.
+ */
+ if (p->static_prio > rq->expired->best_static_prio)
+ return MAX_PRIO;
+ if (!rq->prio_level[uprio])
+ rq->prio_level[uprio] = MAX_RT_PRIO;
+ /*
+ * Only priorities equal to the prio_level and above for their
+ * static_prio are acceptable, and only if it's not better than
+ * a queued better static_prio's prio_level.
+ */
+ if (p->static_prio < array->best_static_prio) {
+ if (likely(p->policy != SCHED_BATCH))
+ array->best_static_prio = p->static_prio;
+ } else if (p->static_prio == array->best_static_prio) {
+ search_prio = minprio(rq, uprio);
+ } else {
+ int i;
+
+ search_prio = minprio(rq, uprio);
+ /* A bound O(n) function, worst case n is 40 */
+ for (i = array->best_static_prio; i <= p->static_prio ; i++) {
+ if (!rq->prio_level[USER_PRIO(i)])
+ rq->prio_level[USER_PRIO(i)] = MAX_RT_PRIO;
+ search_prio = max(search_prio,
+ rq->prio_level[USER_PRIO(i)]);
+ }
+ }
+ if (unlikely(p->policy == SCHED_BATCH)) {
+ search_prio = max(search_prio, p->static_prio);
+ return SCHED_PRIO(find_next_zero_bit(p->bitmap, PRIO_RANGE,
+ USER_PRIO(search_prio)));
+ }
+ bitmap_or(tmp, p->bitmap, prio_matrix[uprio], PRIO_RANGE);
+ return SCHED_PRIO(find_next_zero_bit(tmp, PRIO_RANGE,
+ USER_PRIO(search_prio)));
+}
+
+static void queue_expired(struct task_struct *p, struct rq *rq)
+{
+ task_new_array(p, rq, rq->expired);
+ p->prio = p->normal_prio = first_prio_slot(p);
+ if (p->static_prio < rq->expired->best_static_prio)
+ rq->expired->best_static_prio = p->static_prio;
+ reset_first_time_slice(p);
}
+#ifdef CONFIG_SMP
/*
- * __normal_prio - return the priority that is based on the static
- * priority but is modified by bonuses/penalties.
- *
- * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
- * into the -5 ... 0 ... +5 bonus/penalty range.
- *
- * We use 25% of the full 0...39 priority range so that:
- *
- * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
- * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
- *
- * Both properties are important to certain workloads.
+ * If we're waking up a task that was previously on a different runqueue,
+ * update its data appropriately. Note we may be reading data from src_rq->
+ * outside of lock, but the occasional inaccurate result should be harmless.
*/
+ static void update_if_moved(struct task_struct *p, struct rq *rq)
+{
+ struct rq *src_rq = p->array->rq;
-static inline int __normal_prio(struct task_struct *p)
+ if (src_rq == rq)
+ return;
+ /*
+ * Only need to set p->array when p->rotation == rq->prio_rotation as
+ * they will be set in recalc_task_prio when != rq->prio_rotation.
+ */
+ if (p->rotation == src_rq->prio_rotation) {
+ p->rotation = rq->prio_rotation;
+ if (p->array == src_rq->expired)
+ p->array = rq->expired;
+ else
+ p->array = rq->active;
+ } else
+ p->rotation = 0;
+}
+#else
+static inline void update_if_moved(struct task_struct *p, struct rq *rq)
+{
+}
+#endif
+
+static inline int isoprio_suitable(struct task_struct *p)
{
- int bonus, prio;
+ return !(p->flags & PF_ISOREF);
+}
- bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
+static int task_timeslice(struct task_struct *p);
- prio = p->static_prio - bonus;
- if (prio < MAX_RT_PRIO)
- prio = MAX_RT_PRIO;
- if (prio > MAX_PRIO-1)
- prio = MAX_PRIO-1;
- return prio;
+/*
+ * recalc_task_prio determines what priority a non rt_task will be
+ * queued at. If the task has already been running during this runqueue's
+ * major rotation (rq->prio_rotation) then it continues at the same
+ * priority if it has tick entitlement left. If it does not have entitlement
+ * left, it finds the next priority slot according to its nice value that it
+ * has not extracted quota from. If it has not run during this major
+ * rotation, it starts at the next_entitled_slot and has its bitmap quota
+ * cleared. If it does not have any slots left it has all its slots reset and
+ * is queued on the expired at its first_prio_slot.
+ */
+static void recalc_task_prio(struct task_struct *p, struct rq *rq)
+{
+ struct prio_array *array = rq->active;
+ int queue_prio;
+
+ if (iso_task(p)) {
+ if (isoprio_suitable(p)) {
+ /*
+ * If SCHED_ISO tasks have not used up their real time
+ * quota they have run just better than highest
+ * SCHED_NORMAL priority. Otherwise they run as
+ * SCHED_NORMAL.
+ */
+ p->prio = p->normal_prio = ISO_PRIO;
+ p->array = rq->active;
+ if (p->time_slice <= 0)
+ p->time_slice = p->quota;
+ return;
+ } else if (p->prio == ISO_PRIO) {
+ /* Just about to be demoted to SCHED_NORMAL */
+ p->time_slice = 0;
+ }
+ } else if (idleprio_task(p)) {
+ if (idleprio_suitable(p)) {
+ /*
+ * If suitable idleprio_tasks are queued at MAX_PRIO
+ * only on the idleprio array. Their time_slice is
+ * their full task_timeslice as they cooperatively
+ * multitask.
+ */
+ p->prio = p->normal_prio = MAX_PRIO;
+ p->array = rq->idleprio;
+ if (p->time_slice <= 0)
+ p->time_slice = task_timeslice(p);
+ return;
+ }
+ /*
+ * If unsuitable idleprio_tasks are queued equivalent to
+ * nice 19 tasks on the expired array.
+ */
+ p->flags &= ~PF_NONSLEEP;
+ p->prio = p->normal_prio = MAX_PRIO - 1;
+ p->array = rq->expired;
+ if (p->time_slice <= 0 || p->time_slice > p->quota)
+ p->time_slice = p->quota;
+ return;
+ }
+
+ update_if_moved(p, rq);
+ if (p->rotation == rq->prio_rotation) {
+ if (p->array == array) {
+ if (p->time_slice > 0)
+ return;
+ p->time_slice = p->quota;
+ } else if (p->array == rq->expired) {
+ queue_expired(p, rq);
+ return;
+ } else
+ task_new_array(p, rq, array);
+ } else
+ task_new_array(p, rq, array);
+
+ queue_prio = next_entitled_slot(p, rq);
+ if (queue_prio >= MAX_PRIO) {
+ queue_expired(p, rq);
+ return;
+ }
+ p->prio = p->normal_prio = queue_prio;
+ __set_bit(USER_PRIO(p->prio), p->bitmap);
+}
+
+/*
+ * Adding to a runqueue. The dynamic priority queue that it is added to is
+ * determined by recalc_task_prio() above.
+ */
+static inline void __enqueue_task(struct task_struct *p, struct rq *rq)
+{
+ if (rt_task(p))
+ p->array = rq->active;
+ else
+ recalc_task_prio(p, rq);
+
+ if (idleprio_task(p) && idleprio(p))
+ rq->nr_idleprio++;
+ sched_info_queued(p);
+ set_dynamic_bit(p, rq);
+}
+
+static void enqueue_task(struct task_struct *p, struct rq *rq)
+{
+ __enqueue_task(p, rq);
+ list_add_tail(&p->run_list, p->array->queue + p->prio);
+}
+
+static inline void enqueue_task_head(struct task_struct *p, struct rq *rq)
+{
+ __enqueue_task(p, rq);
+ list_add(&p->run_list, p->array->queue + p->prio);
+}
+
+/*
+ * requeue_task is only called when p->static_prio does not change. p->prio
+ * can change with dynamic tasks.
+ */
+static void requeue_task(struct task_struct *p, struct rq *rq,
+ struct prio_array *old_array, int old_prio)
+{
+ if (p->array == rq->expired)
+ queue_expired(p, rq);
+ list_move_tail(&p->run_list, p->array->queue + p->prio);
+ if (!rt_task(p)) {
+ if (list_empty(old_array->queue + old_prio))
+ __clear_bit(old_prio, old_array->prio_bitmap);
+ set_dynamic_bit(p, rq);
+ }
}
/*
@@ -759,20 +964,29 @@ static inline int __normal_prio(struct t
*/
/*
- * Assume: static_prio_timeslice(NICE_TO_PRIO(0)) == DEF_TIMESLICE
- * If static_prio_timeslice() is ever changed to break this assumption then
- * this code will need modification
- */
-#define TIME_SLICE_NICE_ZERO DEF_TIMESLICE
-#define LOAD_WEIGHT(lp) \
- (((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO)
-#define PRIO_TO_LOAD_WEIGHT(prio) \
- LOAD_WEIGHT(static_prio_timeslice(prio))
-#define RTPRIO_TO_LOAD_WEIGHT(rp) \
- (PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp))
+ * task_timeslice - the total duration a task can run during one major
+ * rotation. Returns value in milliseconds as the smallest value can be 1.
+ */
+static int task_timeslice(struct task_struct *p)
+{
+ int slice = p->quota; /* quota is in us */
+
+ if (!rt_task(p))
+ slice += (PRIO_RANGE - 1 - TASK_USER_PRIO(p)) * slice;
+ return US_TO_MS(slice);
+}
+
+/*
+ * The load weight is basically the task_timeslice in ms. Realtime tasks are
+ * special cased to be proportionately larger than nice -20 by their
+ * rt_priority. The weight for rt tasks can only be arbitrary at best.
+ */
+#define RTPRIO_TO_LOAD_WEIGHT(rp) (rr_interval * 20 * (40 + rp))
static void set_load_weight(struct task_struct *p)
{
+ int load_weight;
+
if (has_rt_policy(p)) {
#ifdef CONFIG_SMP
if (p == task_rq(p)->migration_thread)
@@ -781,12 +995,19 @@ static void set_load_weight(struct task_
* Giving its load any weight will skew balancing
* adversely.
*/
- p->load_weight = 0;
+ load_weight = 0;
else
#endif
- p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
+ load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
} else
- p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio);
+ load_weight = task_timeslice(p);
+ /*
+ * idleprio tasks have much lower weight than SCHED_NORMAL tasks but
+ * still need to be weighted to allow balancing to occur.
+ */
+ if (likely(!idleprio_task(p)))
+ load_weight *= PRIO_RANGE;
+ p->load_weight = load_weight;
}
static inline void
@@ -814,28 +1035,38 @@ static inline void dec_nr_running(struct
}
/*
- * Calculate the expected normal priority: i.e. priority
- * without taking RT-inheritance into account. Might be
- * boosted by interactivity modifiers. Changes upon fork,
- * setprio syscalls, and whenever the interactivity
- * estimator recalculates.
+ * __activate_task - move a task to the runqueue.
*/
-static inline int normal_prio(struct task_struct *p)
+static inline void __activate_task(struct task_struct *p, struct rq *rq)
{
- int prio;
+ enqueue_task(p, rq);
+ inc_nr_running(p, rq);
+}
+/*
+ * __activate_idle_task - move idle task to the _front_ of runqueue.
+ */
+static inline void __activate_idle_task(struct task_struct *p, struct rq *rq)
+{
+ enqueue_task_head(p, rq);
+ inc_nr_running(p, rq);
+}
+
+static inline int normal_prio(struct task_struct *p)
+{
if (has_rt_policy(p))
- prio = MAX_RT_PRIO-1 - p->rt_priority;
+ return MAX_RT_PRIO-1 - p->rt_priority;
+ /* Other tasks all have normal_prio set in recalc_task_prio */
+ if (likely(p->prio >= MAX_RT_PRIO && p->prio < MAX_PRIO))
+ return p->prio;
else
- prio = __normal_prio(p);
- return prio;
+ return p->static_prio;
}
/*
* Calculate the current priority, i.e. the priority
* taken into account by the scheduler. This value might
- * be boosted by RT tasks, or might be boosted by
- * interactivity modifiers. Will be RT if the task got
+ * be boosted by RT tasks as it will be RT if the task got
* RT-boosted. If not then it returns p->normal_prio.
*/
static int effective_prio(struct task_struct *p)
@@ -852,111 +1083,41 @@ static int effective_prio(struct task_st
}
/*
- * __activate_task - move a task to the runqueue.
+ * All tasks have quotas based on rr_interval. RT tasks all get rr_interval.
+ * From nice 1 to 19 they are smaller than it only if they are at least one
+ * tick still. Below nice 0 they get progressively larger.
+ * ie nice -6..0 = rr_interval. nice -10 = 2.5 * rr_interval
+ * nice -20 = 10 * rr_interval. nice 1-19 = rr_interval / 2.
+ * Value returned is in microseconds.
*/
-static void __activate_task(struct task_struct *p, struct rq *rq)
+static inline unsigned int rr_quota(struct task_struct *p)
{
- struct prio_array *target = rq->active;
+ int nice = TASK_NICE(p), rr = rr_interval;
- if (batch_task(p))
- target = rq->expired;
- enqueue_task(p, target);
- inc_nr_running(p, rq);
-}
-
-/*
- * __activate_idle_task - move idle task to the _front_ of runqueue.
- */
-static inline void __activate_idle_task(struct task_struct *p, struct rq *rq)
-{
- enqueue_task_head(p, rq->active);
- inc_nr_running(p, rq);
+ if (!rt_task(p)) {
+ if (nice < -6) {
+ rr *= nice * nice;
+ rr /= 40;
+ } else if (nice > 0)
+ rr = rr / 2 ? : 1;
+ }
+ return MS_TO_US(rr);
}
-/*
- * Recalculate p->normal_prio and p->prio after having slept,
- * updating the sleep-average too:
- */
-static int recalc_task_prio(struct task_struct *p, unsigned long long now)
+/* Every time we set the quota we need to set the load weight */
+static void set_quota(struct task_struct *p)
{
- /* Caller must always ensure 'now >= p->timestamp' */
- unsigned long sleep_time = now - p->timestamp;
-
- if (batch_task(p))
- sleep_time = 0;
-
- if (likely(sleep_time > 0)) {
- /*
- * This ceiling is set to the lowest priority that would allow
- * a task to be reinserted into the active array on timeslice
- * completion.
- */
- unsigned long ceiling = INTERACTIVE_SLEEP(p);
-
- if (p->mm && sleep_time > ceiling && p->sleep_avg < ceiling) {
- /*
- * Prevents user tasks from achieving best priority
- * with one single large enough sleep.
- */
- p->sleep_avg = ceiling;
- /*
- * Using INTERACTIVE_SLEEP() as a ceiling places a
- * nice(0) task 1ms sleep away from promotion, and
- * gives it 700ms to round-robin with no chance of
- * being demoted. This is more than generous, so
- * mark this sleep as non-interactive to prevent the
- * on-runqueue bonus logic from intervening should
- * this task not receive cpu immediately.
- */
- p->sleep_type = SLEEP_NONINTERACTIVE;
- } else {
- /*
- * Tasks waking from uninterruptible sleep are
- * limited in their sleep_avg rise as they
- * are likely to be waiting on I/O
- */
- if (p->sleep_type == SLEEP_NONINTERACTIVE && p->mm) {
- if (p->sleep_avg >= ceiling)
- sleep_time = 0;
- else if (p->sleep_avg + sleep_time >=
- ceiling) {
- p->sleep_avg = ceiling;
- sleep_time = 0;
- }
- }
-
- /*
- * This code gives a bonus to interactive tasks.
- *
- * The boost works by updating the 'average sleep time'
- * value here, based on ->timestamp. The more time a
- * task spends sleeping, the higher the average gets -
- * and the higher the priority boost gets as well.
- */
- p->sleep_avg += sleep_time;
-
- }
- if (p->sleep_avg > NS_MAX_SLEEP_AVG)
- p->sleep_avg = NS_MAX_SLEEP_AVG;
- }
-
- return effective_prio(p);
+ p->quota = rr_quota(p);
+ set_load_weight(p);
}
/*
* activate_task - move a task to the runqueue and do priority recalculation
- *
- * Update all the scheduling statistics stuff. (sleep average
- * calculation, priority modifiers, etc.)
*/
static void activate_task(struct task_struct *p, struct rq *rq, int local)
{
- unsigned long long now;
-
- if (rt_task(p))
- goto out;
+ unsigned long long now = sched_clock();
- now = sched_clock();
#ifdef CONFIG_SMP
if (!local) {
/* Compensate for drifting sched_clock */
@@ -977,32 +1138,9 @@ static void activate_task(struct task_st
(now - p->timestamp) >> 20);
}
- p->prio = recalc_task_prio(p, now);
-
- /*
- * This checks to make sure it's not an uninterruptible task
- * that is now waking up.
- */
- if (p->sleep_type == SLEEP_NORMAL) {
- /*
- * Tasks which were woken up by interrupts (ie. hw events)
- * are most likely of interactive nature. So we give them
- * the credit of extending their sleep time to the period
- * of time they spend on the runqueue, waiting for execution
- * on a CPU, first time around:
- */
- if (in_interrupt())
- p->sleep_type = SLEEP_INTERRUPTED;
- else {
- /*
- * Normal first-time wakeups get a credit too for
- * on-runqueue time, but it will be weighted down:
- */
- p->sleep_type = SLEEP_INTERACTIVE;
- }
- }
+ set_quota(p);
+ p->prio = effective_prio(p);
p->timestamp = now;
-out:
__activate_task(p, rq);
}
@@ -1012,8 +1150,7 @@ out:
static void deactivate_task(struct task_struct *p, struct rq *rq)
{
dec_nr_running(p, rq);
- dequeue_task(p, p->array);
- p->array = NULL;
+ dequeue_task(p, rq);
}
/*
@@ -1095,7 +1232,7 @@ migrate_task(struct task_struct *p, int
* If the task is not on a runqueue (and not running), then
* it is sufficient to simply update the task's cpu field.
*/
- if (!p->array && !task_running(rq, p)) {
+ if (!task_queued(p) && !task_running(rq, p)) {
set_task_cpu(p, dest_cpu);
return 0;
}
@@ -1126,7 +1263,7 @@ void wait_task_inactive(struct task_stru
repeat:
rq = task_rq_lock(p, &flags);
/* Must be off runqueue entirely, not preempted. */
- if (unlikely(p->array || task_running(rq, p))) {
+ if (unlikely(task_queued(p) || task_running(rq, p))) {
/* If it's preempted, we yield. It could be a while. */
preempted = !task_running(rq, p);
task_rq_unlock(rq, &flags);
@@ -1391,6 +1528,31 @@ static inline int wake_idle(int cpu, str
}
#endif
+/*
+ * We need to have a special definition for an idle runqueue when testing
+ * for preemption on CONFIG_HOTPLUG_CPU as the idle task may be scheduled as
+ * a realtime task in sched_idle_next.
+ */
+#ifdef CONFIG_HOTPLUG_CPU
+#define rq_idle(rq) ((rq)->curr == (rq)->idle && !rt_task((rq)->curr))
+#else
+#define rq_idle(rq) ((rq)->curr == (rq)->idle)
+#endif
+
+static inline int task_preempts_curr(struct task_struct *p, struct rq *rq)
+{
+ struct task_struct *curr = rq->curr;
+
+ return ((p->array == task_rq(p)->active &&
+ TASK_PREEMPTS_CURR(p, curr)) || rq_idle(rq));
+}
+
+static inline void try_preempt(struct task_struct *p, struct rq *rq)
+{
+ if (task_preempts_curr(p, rq))
+ resched_task(rq->curr);
+}
+
/***
* try_to_wake_up - wake up a thread
* @p: the to-be-woken-up thread
@@ -1422,7 +1584,7 @@ static int try_to_wake_up(struct task_st
if (!(old_state & state))
goto out;
- if (p->array)
+ if (task_queued(p))
goto out_running;
cpu = task_cpu(p);
@@ -1515,7 +1677,7 @@ out_set_cpu:
old_state = p->state;
if (!(old_state & state))
goto out;
- if (p->array)
+ if (task_queued(p))
goto out_running;
this_cpu = smp_processor_id();
@@ -1524,25 +1686,9 @@ out_set_cpu:
out_activate:
#endif /* CONFIG_SMP */
- if (old_state == TASK_UNINTERRUPTIBLE) {
+ if (old_state == TASK_UNINTERRUPTIBLE)
rq->nr_uninterruptible--;
- /*
- * Tasks on involuntary sleep don't earn
- * sleep_avg beyond just interactive state.
- */
- p->sleep_type = SLEEP_NONINTERACTIVE;
- } else
-
- /*
- * Tasks that have marked their sleep as noninteractive get
- * woken up with their sleep average not weighted in an
- * interactive way.
- */
- if (old_state & TASK_NONINTERACTIVE)
- p->sleep_type = SLEEP_NONINTERACTIVE;
-
- activate_task(p, rq, cpu == this_cpu);
/*
* Sync wakeups (i.e. those types of wakeups where the waker
* has indicated that it will leave the CPU in short order)
@@ -1551,15 +1697,22 @@ out_activate:
* the waker guarantees that the freshly woken up task is going
* to be considered on this CPU.)
*/
- if (!sync || cpu != this_cpu) {
- if (TASK_PREEMPTS_CURR(p, rq))
- resched_task(rq->curr);
- }
+ activate_task(p, rq, cpu == this_cpu);
+ if (!sync || cpu != this_cpu)
+ try_preempt(p, rq);
success = 1;
out_running:
p->state = TASK_RUNNING;
out:
+ /*
+ * Special case when freezing we need to reschedule idleprio tasks
+ * as SCHED_NORMAL or else they'll never freeze
+ */
+ if (idleprio_task(p) && freezing(p) && idleprio(p)) {
+ dequeue_task(p, rq);
+ enqueue_task(p, rq);
+ }
task_rq_unlock(rq, &flags);
return success;
@@ -1577,7 +1730,6 @@ int fastcall wake_up_state(struct task_s
return try_to_wake_up(p, state, 0);
}
-static void task_running_tick(struct rq *rq, struct task_struct *p);
/*
* Perform scheduler related setup for a newly forked process p.
* p is forked by current.
@@ -1605,7 +1757,6 @@ void fastcall sched_fork(struct task_str
p->prio = current->normal_prio;
INIT_LIST_HEAD(&p->run_list);
- p->array = NULL;
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
if (unlikely(sched_info_on()))
memset(&p->sched_info, 0, sizeof(p->sched_info));
@@ -1617,30 +1768,31 @@ void fastcall sched_fork(struct task_str
/* Want to start with kernel preemption disabled. */
task_thread_info(p)->preempt_count = 1;
#endif
+ if (unlikely(p->policy == SCHED_FIFO))
+ goto out;
/*
* Share the timeslice between parent and child, thus the
* total amount of pending timeslices in the system doesn't change,
* resulting in more scheduling fairness.
*/
local_irq_disable();
- p->time_slice = (current->time_slice + 1) >> 1;
- /*
- * The remainder of the first timeslice might be recovered by
- * the parent if the child exits early enough.
- */
- p->first_time_slice = 1;
- current->time_slice >>= 1;
- p->timestamp = sched_clock();
- if (unlikely(!current->time_slice)) {
+ if (current->time_slice > 0) {
+ current->time_slice /= 2;
+ if (current->time_slice)
+ p->time_slice = current->time_slice;
+ else
+ p->time_slice = 1;
/*
- * This case is rare, it happens when the parent has only
- * a single jiffy left from its timeslice. Taking the
- * runqueue lock is not a problem.
+ * The remainder of the first timeslice might be recovered by
+ * the parent if the child exits early enough.
*/
- current->time_slice = 1;
- task_running_tick(cpu_rq(cpu), current);
- }
+ p->first_time_slice = 1;
+ } else
+ p->time_slice = 0;
+
+ p->timestamp = sched_clock();
local_irq_enable();
+out:
put_cpu();
}
@@ -1662,38 +1814,16 @@ void fastcall wake_up_new_task(struct ta
this_cpu = smp_processor_id();
cpu = task_cpu(p);
- /*
- * We decrease the sleep average of forking parents
- * and children as well, to keep max-interactive tasks
- * from forking tasks that are max-interactive. The parent
- * (current) is done further down, under its lock.
- */
- p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
- CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
-
- p->prio = effective_prio(p);
-
if (likely(cpu == this_cpu)) {
+ activate_task(p, rq, 1);
if (!(clone_flags & CLONE_VM)) {
/*
* The VM isn't cloned, so we're in a good position to
* do child-runs-first in anticipation of an exec. This
* usually avoids a lot of COW overhead.
*/
- if (unlikely(!current->array))
- __activate_task(p, rq);
- else {
- p->prio = current->prio;
- p->normal_prio = current->normal_prio;
- list_add_tail(&p->run_list, &current->run_list);
- p->array = current->array;
- p->array->nr_active++;
- inc_nr_running(p, rq);
- }
set_need_resched();
- } else
- /* Run child last */
- __activate_task(p, rq);
+ }
/*
* We skip the following code due to cpu == this_cpu
*
@@ -1710,19 +1840,16 @@ void fastcall wake_up_new_task(struct ta
*/
p->timestamp = (p->timestamp - this_rq->most_recent_timestamp)
+ rq->most_recent_timestamp;
- __activate_task(p, rq);
- if (TASK_PREEMPTS_CURR(p, rq))
- resched_task(rq->curr);
+ activate_task(p, rq, 0);
+ try_preempt(p, rq);
/*
* Parent and child are on different CPUs, now get the
- * parent runqueue to update the parent's ->sleep_avg:
+ * parent runqueue to update the parent's ->flags:
*/
task_rq_unlock(rq, &flags);
this_rq = task_rq_lock(current, &flags);
}
- current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
- PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
task_rq_unlock(this_rq, &flags);
}
@@ -1737,23 +1864,17 @@ void fastcall wake_up_new_task(struct ta
*/
void fastcall sched_exit(struct task_struct *p)
{
+ struct task_struct *parent;
unsigned long flags;
struct rq *rq;
- /*
- * If the child was a (relative-) CPU hog then decrease
- * the sleep_avg of the parent as well.
- */
- rq = task_rq_lock(p->parent, &flags);
- if (p->first_time_slice && task_cpu(p) == task_cpu(p->parent)) {
- p->parent->time_slice += p->time_slice;
- if (unlikely(p->parent->time_slice > task_timeslice(p)))
- p->parent->time_slice = task_timeslice(p);
- }
- if (p->sleep_avg < p->parent->sleep_avg)
- p->parent->sleep_avg = p->parent->sleep_avg /
- (EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg /
- (EXIT_WEIGHT + 1);
+ parent = p->parent;
+ rq = task_rq_lock(parent, &flags);
+ if (p->first_time_slice > 0 && task_cpu(p) == task_cpu(parent)) {
+ parent->time_slice += p->time_slice;
+ if (unlikely(parent->time_slice > parent->quota))
+ parent->time_slice = parent->quota;
+ }
task_rq_unlock(rq, &flags);
}
@@ -2085,23 +2206,17 @@ void sched_exec(void)
* pull_task - move a task from a remote runqueue to the local runqueue.
* Both runqueues must be locked.
*/
-static void pull_task(struct rq *src_rq, struct prio_array *src_array,
- struct task_struct *p, struct rq *this_rq,
- struct prio_array *this_array, int this_cpu)
+static void pull_task(struct rq *src_rq, struct task_struct *p,
+ struct rq *this_rq, int this_cpu)
{
- dequeue_task(p, src_array);
+ dequeue_task(p, src_rq);
dec_nr_running(p, src_rq);
set_task_cpu(p, this_cpu);
inc_nr_running(p, this_rq);
- enqueue_task(p, this_array);
+ enqueue_task(p, this_rq);
p->timestamp = (p->timestamp - src_rq->most_recent_timestamp)
+ this_rq->most_recent_timestamp;
- /*
- * Note that idle threads have a prio of MAX_PRIO, for this test
- * to be always true for them.
- */
- if (TASK_PREEMPTS_CURR(p, this_rq))
- resched_task(this_rq->curr);
+ try_preempt(p, this_rq);
}
/*
@@ -2144,7 +2259,16 @@ int can_migrate_task(struct task_struct
return 1;
}
-#define rq_best_prio(rq) min((rq)->curr->prio, (rq)->best_expired_prio)
+static inline int rq_best_prio(struct rq *rq)
+{
+ int best_prio, exp_prio;
+
+ best_prio = sched_find_first_bit(rq->dyn_bitmap);
+ exp_prio = find_next_bit(rq->exp_bitmap, MAX_PRIO, MAX_RT_PRIO);
+ if (unlikely(best_prio > exp_prio))
+ best_prio = exp_prio;
+ return best_prio;
+}
/*
* move_tasks tries to move up to max_nr_move tasks and max_load_move weighted
@@ -2160,7 +2284,7 @@ static int move_tasks(struct rq *this_rq
{
int idx, pulled = 0, pinned = 0, this_best_prio, best_prio,
best_prio_seen, skip_for_load;
- struct prio_array *array, *dst_array;
+ struct prio_array *array;
struct list_head *head, *curr;
struct task_struct *tmp;
long rem_load_move;
@@ -2187,31 +2311,29 @@ static int move_tasks(struct rq *this_rq
* be cache-cold, thus switching CPUs has the least effect
* on them.
*/
- if (busiest->expired->nr_active) {
- array = busiest->expired;
- dst_array = this_rq->expired;
- } else {
- array = busiest->active;
- dst_array = this_rq->active;
- }
-
+ array = busiest->expired;
new_array:
- /* Start searching at priority 0: */
- idx = 0;
+ /* Expired arrays don't have RT tasks so they're always MAX_RT_PRIO+ */
+ if (array == busiest->expired)
+ idx = MAX_RT_PRIO;
+ else
+ idx = 0;
skip_bitmap:
if (!idx)
- idx = sched_find_first_bit(array->bitmap);
+ idx = sched_find_first_bit(array->prio_bitmap);
else
- idx = find_next_bit(array->bitmap, MAX_PRIO, idx);
- if (idx >= MAX_PRIO) {
- if (array == busiest->expired && busiest->active->nr_active) {
+ idx = find_next_bit(array->prio_bitmap, MAX_PRIO, idx);
+ if (idx == MAX_PRIO) {
+ if (array == busiest->idleprio && busiest->nr_idleprio)
+ goto found_idleprio;
+ if (array == busiest->expired) {
array = busiest->active;
- dst_array = this_rq->active;
goto new_array;
}
goto out;
}
+found_idleprio:
head = array->queue + idx;
curr = head->prev;
skip_queue:
@@ -2233,11 +2355,22 @@ skip_queue:
best_prio_seen |= idx == best_prio;
if (curr != head)
goto skip_queue;
+ if (idx == MAX_PRIO) {
+ /*
+ * Occurs either when balancing idleprio tasks or
+ * there really are no more tasks to find.
+ */
+ if (array == busiest->expired) {
+ array = busiest->active;
+ goto new_array;
+ }
+ goto out;
+ }
idx++;
goto skip_bitmap;
}
- pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
+ pull_task(busiest, tmp, this_rq, this_cpu);
pulled++;
rem_load_move -= tmp->load_weight;
@@ -2250,6 +2383,13 @@ skip_queue:
this_best_prio = idx;
if (curr != head)
goto skip_queue;
+ if (idx == MAX_PRIO) {
+ if (array == busiest->expired) {
+ array = busiest->active;
+ goto new_array;
+ }
+ goto out;
+ }
idx++;
goto skip_bitmap;
}
@@ -3013,11 +3153,36 @@ EXPORT_PER_CPU_SYMBOL(kstat);
/*
* This is called on clock ticks and on context switches.
* Bank in p->sched_time the ns elapsed since the last tick or switch.
+ * CPU scheduler quota accounting is also performed here in microseconds.
+ * The value returned from sched_clock() occasionally gives bogus values so
+ * some sanity checking is required.
*/
-static inline void
-update_cpu_clock(struct task_struct *p, struct rq *rq, unsigned long long now)
+static void
+update_cpu_clock(struct task_struct *p, struct rq *rq, unsigned long long now,
+ int tick)
{
- p->sched_time += now - p->last_ran;
+ long time_diff = now - p->last_ran;
+
+ if (tick) {
+ /*
+ * Called from scheduler_tick() there should be less than two
+ * jiffies worth, and not negative/overflow.
+ */
+ if (time_diff > JIFFIES_TO_NS(2) || time_diff < 0)
+ time_diff = JIFFIES_TO_NS(1);
+ } else {
+ /*
+ * Called from context_switch there should be less than one
+ * jiffy worth, and not negative/overflow. There should be
+ * some time banked here so use a nominal 1us.
+ */
+ if (time_diff > JIFFIES_TO_NS(1) || time_diff < 1)
+ time_diff = 1000;
+ }
+ /* time_slice accounting is done in usecs to avoid overflow on 32bit */
+ if (p != rq->idle && p->policy != SCHED_FIFO)
+ p->time_slice -= time_diff / 1000;
+ p->sched_time += time_diff;
p->last_ran = rq->most_recent_timestamp = now;
}
@@ -3038,27 +3203,6 @@ unsigned long long current_sched_time(co
}
/*
- * We place interactive tasks back into the active array, if possible.
- *
- * To guarantee that this does not starve expired tasks we ignore the
- * interactivity of a task if the first expired task had to wait more
- * than a 'reasonable' amount of time. This deadline timeout is
- * load-dependent, as the frequency of array switched decreases with
- * increasing number of running tasks. We also ignore the interactivity
- * if a better static_prio task has expired:
- */
-static inline int expired_starving(struct rq *rq)
-{
- if (rq->curr->static_prio > rq->best_expired_prio)
- return 1;
- if (!STARVATION_LIMIT || !rq->expired_timestamp)
- return 0;
- if (jiffies - rq->expired_timestamp > STARVATION_LIMIT * rq->nr_running)
- return 1;
- return 0;
-}
-
-/*
* Account user cpu time to a process.
* @p: the process that the cpu time gets accounted to
* @hardirq_offset: the offset to subtract from hardirq_count()
@@ -3073,7 +3217,7 @@ void account_user_time(struct task_struc
/* Add user time to cpustat. */
tmp = cputime_to_cputime64(cputime);
- if (TASK_NICE(p) > 0)
+ if (TASK_NICE(p) > 0 || idleprio_task(p))
cpustat->nice = cputime64_add(cpustat->nice, tmp);
else
cpustat->user = cputime64_add(cpustat->user, tmp);
@@ -3131,87 +3275,94 @@ void account_steal_time(struct task_stru
cpustat->steal = cputime64_add(cpustat->steal, tmp);
}
-static void task_running_tick(struct rq *rq, struct task_struct *p)
+/*
+ * The task has used up its quota of running in this prio_level so it must be
+ * dropped a priority level, all managed by recalc_task_prio().
+ */
+static void task_expired_entitlement(struct rq *rq, struct task_struct *p)
{
- if (p->array != rq->active) {
- /* Task has expired but was not scheduled yet */
- set_tsk_need_resched(p);
+ int overrun;
+
+ reset_first_time_slice(p);
+ if (rt_task(p)) {
+ p->time_slice += p->quota;
+ list_move_tail(&p->run_list, p->array->queue + p->prio);
return;
}
- spin_lock(&rq->lock);
+ overrun = p->time_slice;
+ dequeue_task(p, rq);
+ enqueue_task(p, rq);
/*
- * The task was running during this tick - update the
- * time slice counter. Note: we do not update a thread's
- * priority until it either goes to sleep or uses up its
- * timeslice. This makes it possible for interactive tasks
- * to use up their timeslices at their highest priority levels.
+ * Subtract any extra time this task ran over its time_slice; ie
+ * overrun will either be 0 or negative.
*/
- if (rt_task(p)) {
- /*
- * RR tasks need a special form of timeslice management.
- * FIFO tasks have no timeslices.
- */
- if ((p->policy == SCHED_RR) && !--p->time_slice) {
- p->time_slice = task_timeslice(p);
- p->first_time_slice = 0;
- set_tsk_need_resched(p);
+ p->time_slice += overrun;
+}
- /* put it at the end of the queue: */
- requeue_task(p, rq->active);
- }
- goto out_unlock;
+/*
+ * Test if SCHED_ISO tasks have run longer than their alloted period as RT
+ * tasks and set the refractory flag if necessary. There is 10% hysteresis
+ * for unsetting the flag.
+ */
+static unsigned int test_ret_isorefractory(struct rq *rq)
+{
+ if (likely(!rq->iso_refractory)) {
+ if (rq->iso_ticks / ISO_PERIOD > sched_iso_cpu)
+ rq->iso_refractory = 1;
+ } else {
+ if (rq->iso_ticks / ISO_PERIOD < (sched_iso_cpu * 90 / 100))
+ rq->iso_refractory = 0;
}
- if (!--p->time_slice) {
- dequeue_task(p, rq->active);
- set_tsk_need_resched(p);
- p->prio = effective_prio(p);
- p->time_slice = task_timeslice(p);
- p->first_time_slice = 0;
+ return rq->iso_refractory;
+}
- if (!rq->expired_timestamp)
- rq->expired_timestamp = jiffies;
- if (!TASK_INTERACTIVE(p) || expired_starving(rq)) {
- enqueue_task(p, rq->expired);
- if (p->static_prio < rq->best_expired_prio)
- rq->best_expired_prio = p->static_prio;
- } else
- enqueue_task(p, rq->active);
- } else {
- /*
- * Prevent a too long timeslice allowing a task to monopolize
- * the CPU. We do this by splitting up the timeslice into
- * smaller pieces.
- *
- * Note: this does not mean the task's timeslices expire or
- * get lost in any way, they just might be preempted by
- * another task of equal priority. (one with higher
- * priority would have preempted this task already.) We
- * requeue this task to the end of the list on this priority
- * level, which is in essence a round-robin of tasks with
- * equal priority.
- *
- * This only applies to tasks in the interactive
- * delta range with at least TIMESLICE_GRANULARITY to requeue.
- */
- if (TASK_INTERACTIVE(p) && !((task_timeslice(p) -
- p->time_slice) % TIMESLICE_GRANULARITY(p)) &&
- (p->time_slice >= TIMESLICE_GRANULARITY(p)) &&
- (p->array == rq->active)) {
+/* No SCHED_ISO task was running so decrease rq->iso_ticks */
+static inline void no_iso_tick(struct rq *rq)
+{
+ rq->iso_ticks = rq->iso_ticks * (ISO_PERIOD - 1) / ISO_PERIOD;
+}
- requeue_task(p, rq->active);
- set_tsk_need_resched(p);
- }
+/* This manages tasks that have run out of timeslice during a scheduler_tick */
+static void task_running_tick(struct rq *rq, struct task_struct *p)
+{
+ /*
+ * If a SCHED_ISO task is running we increment the iso_ticks. In
+ * order to prevent SCHED_ISO tasks from causing starvation in the
+ * presence of true RT tasks we account those as iso_ticks as well.
+ */
+ if ((rt_task(p) || (iso_task(p) && !rq->iso_refractory))) {
+ if (rq->iso_ticks <= (ISO_PERIOD * 100) - 100)
+ rq->iso_ticks += 100;
+ } else
+ no_iso_tick(rq);
+
+ if (iso_task(p)) {
+ if (unlikely(test_ret_isorefractory(rq))) {
+ if (isoprio_suitable(p)) {
+ /*
+ * SCHED_ISO task is running as RT and limit
+ * has been hit. Set the PF_ISOREF flag and
+ * force it to reschedule as SCHED_NORMAL
+ * by zeroing its time_slice
+ */
+ p->flags |= PF_ISOREF;
+ p->time_slice = 0;
+ }
+ } else
+ p->flags &= ~PF_ISOREF;
}
-out_unlock:
- spin_unlock(&rq->lock);
+ /* SCHED_FIFO tasks never run out of timeslice. */
+ if (p->time_slice > 0 || p->policy == SCHED_FIFO)
+ return;
+ /* p->time_slice <= 0 */
+ set_tsk_need_resched(p);
+ if (likely(task_queued(p)))
+ task_expired_entitlement(rq, p);
}
/*
* This function gets called by the timer code, with HZ frequency.
* We call it with interrupts disabled.
- *
- * It also gets called by the fork code, when changing the parent's
- * timeslices.
*/
void scheduler_tick(void)
{
@@ -3220,10 +3371,14 @@ void scheduler_tick(void)
int cpu = smp_processor_id();
struct rq *rq = cpu_rq(cpu);
- update_cpu_clock(p, rq, now);
+ update_cpu_clock(p, rq, now, 1);
+ spin_lock(&rq->lock);
if (p != rq->idle)
task_running_tick(rq, p);
+ else
+ no_iso_tick(rq);
+ spin_unlock(&rq->lock);
#ifdef CONFIG_SMP
update_load(rq);
if (time_after_eq(jiffies, rq->next_balance))
@@ -3269,10 +3424,80 @@ EXPORT_SYMBOL(sub_preempt_count);
#endif
-static inline int interactive_sleep(enum sleep_type sleep_type)
+static void reset_prio_levels(struct rq *rq)
+{
+ rq->active->best_static_prio = MAX_PRIO - 1;
+ rq->expired->best_static_prio = MAX_PRIO - 1;
+ memset(rq->prio_level, 0, sizeof(int) * PRIO_RANGE);
+}
+
+/*
+ * Only tasks running are SCHED_IDLEPRIO. Set the active array to the
+ * idleprio array and if it isn't already active
+ */
+static struct task_struct *next_idleprio_task(struct rq *rq)
{
- return (sleep_type == SLEEP_INTERACTIVE ||
- sleep_type == SLEEP_INTERRUPTED);
+ struct prio_array *array = rq->active;
+ struct list_head *queue;
+
+ if (array != rq->idleprio) {
+ rq->active = rq->idleprio;
+ rq->expired = array;
+ array = rq->active;
+ rq->exp_bitmap = rq->expired->prio_bitmap;
+ rq->dyn_bitmap = rq->active->prio_bitmap;
+ }
+ rq->prio_rotation++;
+ reset_prio_levels(rq);
+ queue = array->queue + MAX_PRIO;
+ return list_entry(queue->next, struct task_struct, run_list);
+}
+
+/*
+ * next_dynamic_task finds the next suitable dynamic task.
+ */
+static inline struct task_struct *next_dynamic_task(struct rq *rq, int idx)
+{
+ struct prio_array *array = rq->active;
+ struct task_struct *next;
+ struct list_head *queue;
+ int nstatic;
+
+retry:
+ if (unlikely(rq->nr_running == rq->nr_idleprio))
+ return next_idleprio_task(rq);
+ if (idx >= MAX_PRIO) {
+ /* There are no more tasks in the active array. Swap arrays */
+ array = rq->expired;
+ rq->expired = rq->active;
+ rq->active = array;
+ rq->exp_bitmap = rq->expired->prio_bitmap;
+ rq->dyn_bitmap = rq->active->prio_bitmap;
+ rq->prio_rotation++;
+ idx = find_next_bit(rq->dyn_bitmap, MAX_PRIO, MAX_RT_PRIO);
+ reset_prio_levels(rq);
+ }
+ queue = array->queue + idx;
+ next = list_entry(queue->next, struct task_struct, run_list);
+ if (unlikely(next->time_slice <= 0 && !(iso_task(next) &&
+ isoprio_suitable(next)))) {
+ /*
+ * Unlucky enough that this task ran out of time_slice
+ * before it hit a scheduler_tick so it should have its
+ * priority reassessed and choose another task (possibly
+ * the same one)
+ */
+ task_expired_entitlement(rq, next);
+ idx = find_next_bit(rq->dyn_bitmap, MAX_PRIO, MAX_RT_PRIO);
+ goto retry;
+ }
+ next->rotation = rq->prio_rotation;
+ nstatic = next->static_prio;
+ if (nstatic < array->best_static_prio)
+ array->best_static_prio = nstatic;
+ if (idx > rq->prio_level[USER_PRIO(nstatic)])
+ rq->prio_level[USER_PRIO(nstatic)] = idx;
+ return next;
}
/*
@@ -3281,13 +3506,11 @@ static inline int interactive_sleep(enum
asmlinkage void __sched schedule(void)
{
struct task_struct *prev, *next;
- struct prio_array *array;
struct list_head *queue;
unsigned long long now;
- unsigned long run_time;
- int cpu, idx, new_prio;
long *switch_count;
struct rq *rq;
+ int cpu, idx;
/*
* Test if we are atomic. Since do_exit() needs to call into
@@ -3323,18 +3546,6 @@ need_resched_nonpreemptible:
schedstat_inc(rq, sched_cnt);
now = sched_clock();
- if (likely((long long)(now - prev->timestamp) < NS_MAX_SLEEP_AVG)) {
- run_time = now - prev->timestamp;
- if (unlikely((long long)(now - prev->timestamp) < 0))
- run_time = 0;
- } else
- run_time = NS_MAX_SLEEP_AVG;
-
- /*
- * Tasks charged proportionately less run_time at high sleep_avg to
- * delay them losing their interactive status
- */
- run_time /= (CURRENT_BONUS(prev) ? : 1);
spin_lock_irq(&rq->lock);
@@ -3345,8 +3556,10 @@ need_resched_nonpreemptible:
unlikely(signal_pending(prev))))
prev->state = TASK_RUNNING;
else {
- if (prev->state == TASK_UNINTERRUPTIBLE)
+ if (prev->state == TASK_UNINTERRUPTIBLE) {
+ prev->flags |= PF_NONSLEEP;
rq->nr_uninterruptible++;
+ }
deactivate_task(prev, rq);
}
}
@@ -3356,59 +3569,29 @@ need_resched_nonpreemptible:
idle_balance(cpu, rq);
if (!rq->nr_running) {
next = rq->idle;
- rq->expired_timestamp = 0;
goto switch_tasks;
}
}
- array = rq->active;
- if (unlikely(!array->nr_active)) {
- /*
- * Switch the active and expired arrays.
- */
- schedstat_inc(rq, sched_switch);
- rq->active = rq->expired;
- rq->expired = array;
- array = rq->active;
- rq->expired_timestamp = 0;
- rq->best_expired_prio = MAX_PRIO;
+ idx = sched_find_first_bit(rq->dyn_bitmap);
+ if (likely(idx > ISO_PRIO))
+ next = next_dynamic_task(rq, idx);
+ else {
+ queue = rq->active->queue + idx;
+ next = list_entry(queue->next, struct task_struct, run_list);
}
-
- idx = sched_find_first_bit(array->bitmap);
- queue = array->queue + idx;
- next = list_entry(queue->next, struct task_struct, run_list);
-
- if (!rt_task(next) && interactive_sleep(next->sleep_type)) {
- unsigned long long delta = now - next->timestamp;
- if (unlikely((long long)(now - next->timestamp) < 0))
- delta = 0;
-
- if (next->sleep_type == SLEEP_INTERACTIVE)
- delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;
-
- array = next->array;
- new_prio = recalc_task_prio(next, next->timestamp + delta);
-
- if (unlikely(next->prio != new_prio)) {
- dequeue_task(next, array);
- next->prio = new_prio;
- enqueue_task(next, array);
- }
- }
- next->sleep_type = SLEEP_NORMAL;
switch_tasks:
- if (next == rq->idle)
+ if (next == rq->idle) {
+ reset_prio_levels(rq);
+ rq->prio_rotation++;
schedstat_inc(rq, sched_goidle);
+ }
prefetch(next);
prefetch_stack(next);
clear_tsk_need_resched(prev);
rcu_qsctr_inc(task_cpu(prev));
- update_cpu_clock(prev, rq, now);
-
- prev->sleep_avg -= run_time;
- if ((long)prev->sleep_avg <= 0)
- prev->sleep_avg = 0;
+ update_cpu_clock(prev, rq, now, 0);
prev->timestamp = prev->last_ran = now;
sched_info_switch(prev, next);
@@ -3844,29 +4027,22 @@ EXPORT_SYMBOL(sleep_on_timeout);
*/
void rt_mutex_setprio(struct task_struct *p, int prio)
{
- struct prio_array *array;
unsigned long flags;
+ int queued, oldprio;
struct rq *rq;
- int oldprio;
BUG_ON(prio < 0 || prio > MAX_PRIO);
rq = task_rq_lock(p, &flags);
oldprio = p->prio;
- array = p->array;
- if (array)
- dequeue_task(p, array);
+ queued = task_queued(p);
+ if (queued)
+ dequeue_task(p, rq);
p->prio = prio;
- if (array) {
- /*
- * If changing to an RT priority then queue it
- * in the active array!
- */
- if (rt_task(p))
- array = rq->active;
- enqueue_task(p, array);
+ if (queued) {
+ enqueue_task(p, rq);
/*
* Reschedule if we are currently running on this runqueue and
* our priority decreased, or if we are not currently running on
@@ -3875,8 +4051,8 @@ void rt_mutex_setprio(struct task_struct
if (task_running(rq, p)) {
if (p->prio > oldprio)
resched_task(rq->curr);
- } else if (TASK_PREEMPTS_CURR(p, rq))
- resched_task(rq->curr);
+ } else
+ try_preempt(p, rq);
}
task_rq_unlock(rq, &flags);
}
@@ -3885,8 +4061,7 @@ void rt_mutex_setprio(struct task_struct
void set_user_nice(struct task_struct *p, long nice)
{
- struct prio_array *array;
- int old_prio, delta;
+ int queued, old_prio,delta;
unsigned long flags;
struct rq *rq;
@@ -3907,26 +4082,27 @@ void set_user_nice(struct task_struct *p
p->static_prio = NICE_TO_PRIO(nice);
goto out_unlock;
}
- array = p->array;
- if (array) {
- dequeue_task(p, array);
+ queued = task_queued(p);
+ if (queued) {
+ dequeue_task(p, rq);
dec_raw_weighted_load(rq, p);
}
p->static_prio = NICE_TO_PRIO(nice);
- set_load_weight(p);
old_prio = p->prio;
p->prio = effective_prio(p);
+ set_quota(p);
delta = p->prio - old_prio;
- if (array) {
- enqueue_task(p, array);
+ if (queued) {
+ enqueue_task(p, rq);
inc_raw_weighted_load(rq, p);
/*
* If the task increased its priority or is running and
* lowered its priority, then reschedule its CPU:
*/
- if (delta < 0 || (delta > 0 && task_running(rq, p)))
+ if (delta < 0 || ((delta > 0 || idleprio_task(p)) &&
+ task_running(rq, p)))
resched_task(rq->curr);
}
out_unlock:
@@ -3996,7 +4172,7 @@ asmlinkage long sys_nice(int increment)
*
* This is the priority value as seen by users in /proc.
* RT tasks are offset by -200. Normal tasks are centered
- * around 0, value goes from -16 to +15.
+ * around 0, value goes from 0 to +39.
*/
int task_prio(const struct task_struct *p)
{
@@ -4043,19 +4219,14 @@ static inline struct task_struct *find_p
/* Actually do priority change: must hold rq lock. */
static void __setscheduler(struct task_struct *p, int policy, int prio)
{
- BUG_ON(p->array);
+ BUG_ON(task_queued(p));
p->policy = policy;
p->rt_priority = prio;
p->normal_prio = normal_prio(p);
/* we are holding p->pi_lock already */
p->prio = rt_mutex_getprio(p);
- /*
- * SCHED_BATCH tasks are treated as perpetual CPU hogs:
- */
- if (policy == SCHED_BATCH)
- p->sleep_avg = 0;
- set_load_weight(p);
+ set_quota(p);
}
/**
@@ -4069,19 +4240,27 @@ static void __setscheduler(struct task_s
int sched_setscheduler(struct task_struct *p, int policy,
struct sched_param *param)
{
- int retval, oldprio, oldpolicy = -1;
- struct prio_array *array;
+ struct sched_param zero_param = { .sched_priority = 0 };
+ int queued, retval, oldprio, oldpolicy = -1;
unsigned long flags;
struct rq *rq;
/* may grab non-irq protected spin_locks */
BUG_ON(in_interrupt());
+ if (is_rt_policy(policy) && !capable(CAP_SYS_NICE)) {
+ /*
+ * If the caller requested an RT policy without having the
+ * necessary rights, we downgrade the policy to SCHED_ISO.
+ * We also set the parameter to zero to pass the checks.
+ */
+ policy = SCHED_ISO;
+ param = &zero_param;
+ }
recheck:
/* double check policy once rq lock held */
if (policy < 0)
policy = oldpolicy = p->policy;
- else if (policy != SCHED_FIFO && policy != SCHED_RR &&
- policy != SCHED_NORMAL && policy != SCHED_BATCH)
+ else if (!SCHED_RANGE(policy))
return -EINVAL;
/*
* Valid priorities for SCHED_FIFO and SCHED_RR are
@@ -4116,6 +4295,31 @@ recheck:
if (param->sched_priority > p->rt_priority &&
param->sched_priority > rlim_rtprio)
return -EPERM;
+ } else {
+ switch (p->policy) {
+ /*
+ * Can only downgrade policies but not back to
+ * SCHED_NORMAL
+ */
+ case SCHED_ISO:
+ if (policy == SCHED_ISO)
+ goto out;
+ if (policy == SCHED_NORMAL)
+ return -EPERM;
+ break;
+ case SCHED_BATCH:
+ if (policy == SCHED_BATCH)
+ goto out;
+ if (policy != SCHED_IDLEPRIO)
+ return -EPERM;
+ break;
+ case SCHED_IDLEPRIO:
+ if (policy == SCHED_IDLEPRIO)
+ goto out;
+ return -EPERM;
+ default:
+ break;
+ }
}
/* can't change other user's priorities */
@@ -4124,6 +4328,11 @@ recheck:
return -EPERM;
}
+ if (!(p->mm) && policy == SCHED_IDLEPRIO) {
+ /* Don't allow kernel threads to be SCHED_IDLEPRIO. */
+ return -EINVAL;
+ }
+
retval = security_task_setscheduler(p, policy, param);
if (retval)
return retval;
@@ -4144,12 +4353,12 @@ recheck:
spin_unlock_irqrestore(&p->pi_lock, flags);
goto recheck;
}
- array = p->array;
- if (array)
+ queued = task_queued(p);
+ if (queued)
deactivate_task(p, rq);
oldprio = p->prio;
__setscheduler(p, policy, param->sched_priority);
- if (array) {
+ if (queued) {
__activate_task(p, rq);
/*
* Reschedule if we are currently running on this runqueue and
@@ -4159,14 +4368,15 @@ recheck:
if (task_running(rq, p)) {
if (p->prio > oldprio)
resched_task(rq->curr);
- } else if (TASK_PREEMPTS_CURR(p, rq))
- resched_task(rq->curr);
+ } else
+ try_preempt(p, rq);
}
__task_rq_unlock(rq);
spin_unlock_irqrestore(&p->pi_lock, flags);
rt_mutex_adjust_pi(p);
+out:
return 0;
}
EXPORT_SYMBOL_GPL(sched_setscheduler);
@@ -4433,41 +4643,34 @@ asmlinkage long sys_sched_getaffinity(pi
* sys_sched_yield - yield the current processor to other threads.
*
* This function yields the current CPU by moving the calling thread
- * to the expired array. If there are no other threads running on this
- * CPU then this function will return.
+ * to the expired array if SCHED_NORMAL or the end of its current priority
+ * queue if a realtime task. If there are no other threads running on this
+ * cpu this function will return.
*/
asmlinkage long sys_sched_yield(void)
{
struct rq *rq = this_rq_lock();
- struct prio_array *array = current->array, *target = rq->expired;
+ struct task_struct *p = current;
schedstat_inc(rq, yld_cnt);
- /*
- * We implement yielding by moving the task into the expired
- * queue.
- *
- * (special rule: RT tasks will just roundrobin in the active
- * array.)
- */
- if (rt_task(current))
- target = rq->active;
-
- if (array->nr_active == 1) {
- schedstat_inc(rq, yld_act_empty);
- if (!rq->expired->nr_active)
- schedstat_inc(rq, yld_both_empty);
- } else if (!rq->expired->nr_active)
- schedstat_inc(rq, yld_exp_empty);
-
- if (array != target) {
- dequeue_task(current, array);
- enqueue_task(current, target);
- } else
- /*
- * requeue_task is cheaper so perform that if possible.
- */
- requeue_task(current, array);
+ if (rq->nr_running == 1)
+ schedstat_inc(rq, yld_both_empty);
+ else {
+ struct prio_array *old_array = p->array;
+ int old_prio = p->prio;
+
+ if (idleprio_task(p)) {
+ dequeue_task(p, rq);
+ enqueue_task(p, rq);
+ goto out_release;
+ }
+ /* p->prio will be updated in requeue_task via queue_expired */
+ if (!rt_task(p))
+ p->array = rq->expired;
+ requeue_task(p, rq, old_array, old_prio);
+ }
+out_release:
/*
* Since we are going to call schedule() anyway, there's
* no need to preempt or enable interrupts:
@@ -4619,6 +4822,8 @@ asmlinkage long sys_sched_get_priority_m
break;
case SCHED_NORMAL:
case SCHED_BATCH:
+ case SCHED_ISO:
+ case SCHED_IDLEPRIO:
ret = 0;
break;
}
@@ -4643,6 +4848,8 @@ asmlinkage long sys_sched_get_priority_m
break;
case SCHED_NORMAL:
case SCHED_BATCH:
+ case SCHED_ISO:
+ case SCHED_IDLEPRIO:
ret = 0;
}
return ret;
@@ -4676,8 +4883,8 @@ long sys_sched_rr_get_interval(pid_t pid
if (retval)
goto out_unlock;
- jiffies_to_timespec(p->policy == SCHED_FIFO ?
- 0 : task_timeslice(p), &t);
+ t = ns_to_timespec(p->policy == SCHED_FIFO ? 0 :
+ MS_TO_NS(task_timeslice(p)));
read_unlock(&tasklist_lock);
retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
out_nounlock:
@@ -4771,10 +4978,10 @@ void __cpuinit init_idle(struct task_str
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
- idle->timestamp = sched_clock();
- idle->sleep_avg = 0;
- idle->array = NULL;
- idle->prio = idle->normal_prio = MAX_PRIO;
+ bitmap_zero(idle->bitmap, PRIO_RANGE);
+ idle->timestamp = idle->last_ran = sched_clock();
+ idle->array = rq->active;
+ idle->prio = idle->normal_prio = NICE_TO_PRIO(0);
idle->state = TASK_RUNNING;
idle->cpus_allowed = cpumask_of_cpu(cpu);
set_task_cpu(idle, cpu);
@@ -4893,7 +5100,7 @@ static int __migrate_task(struct task_st
goto out;
set_task_cpu(p, dest_cpu);
- if (p->array) {
+ if (task_queued(p)) {
/*
* Sync timestamp with rq_dest's before activating.
* The same thing could be achieved by doing this step
@@ -4904,8 +5111,7 @@ static int __migrate_task(struct task_st
+ rq_dest->most_recent_timestamp;
deactivate_task(p, rq_src);
__activate_task(p, rq_dest);
- if (TASK_PREEMPTS_CURR(p, rq_dest))
- resched_task(rq_dest->curr);
+ try_preempt(p, rq_dest);
}
ret = 1;
out:
@@ -5194,7 +5400,7 @@ migration_call(struct notifier_block *nf
/* Idle task back to normal (off runqueue, low prio) */
rq = task_rq_lock(rq->idle, &flags);
deactivate_task(rq->idle, rq);
- rq->idle->static_prio = MAX_PRIO;
+ rq->idle->static_prio = NICE_TO_PRIO(0);
__setscheduler(rq->idle, SCHED_NORMAL, 0);
migrate_dead_tasks(cpu);
task_rq_unlock(rq, &flags);
@@ -6706,6 +6912,13 @@ void __init sched_init_smp(void)
/* Move init over to a non-isolated CPU */
if (set_cpus_allowed(current, non_isolated_cpus) < 0)
BUG();
+
+ /*
+ * Assume that every added cpu gives us slightly less overall latency
+ * allowing us to increase the base rr_interval, but in a non linear
+ * fashion.
+ */
+ rr_interval *= 1 + ilog2(num_online_cpus());
}
#else
void __init sched_init_smp(void)
@@ -6727,6 +6940,16 @@ void __init sched_init(void)
{
int i, j, k;
+ /* Generate the priority matrix */
+ for (i = 0; i < PRIO_RANGE; i++) {
+ bitmap_fill(prio_matrix[i], PRIO_RANGE);
+ j = PRIO_RANGE * PRIO_RANGE / (PRIO_RANGE - i);
+ for (k = 0; k <= PRIO_RANGE * (PRIO_RANGE - 1); k += j) {
+ __clear_bit(PRIO_RANGE - 1 - (k / PRIO_RANGE),
+ prio_matrix[i]);
+ }
+ }
+
for_each_possible_cpu(i) {
struct prio_array *array;
struct rq *rq;
@@ -6734,12 +6957,20 @@ void __init sched_init(void)
rq = cpu_rq(i);
spin_lock_init(&rq->lock);
lockdep_set_class(&rq->lock, &rq->rq_lock_key);
+ rq->iso_ticks = 0;
rq->nr_running = 0;
+ rq->nr_idleprio = 0;
+ rq->prio_rotation = 0;
rq->active = rq->arrays;
+ rq->idleprio = rq->active;
rq->expired = rq->arrays + 1;
- rq->best_expired_prio = MAX_PRIO;
+ reset_prio_levels(rq);
+ rq->dyn_bitmap = rq->active->prio_bitmap;
+ rq->exp_bitmap = rq->expired->prio_bitmap;
#ifdef CONFIG_SMP
+ rq->active->rq = rq;
+ rq->expired->rq = rq;
rq->sd = NULL;
for (j = 1; j < 3; j++)
rq->cpu_load[j] = 0;
@@ -6752,16 +6983,16 @@ void __init sched_init(void)
atomic_set(&rq->nr_iowait, 0);
for (j = 0; j < 2; j++) {
+
array = rq->arrays + j;
- for (k = 0; k < MAX_PRIO; k++) {
+ for (k = 0; k <= MAX_PRIO; k++)
INIT_LIST_HEAD(array->queue + k);
- __clear_bit(k, array->bitmap);
- }
- // delimiter for bitsearch
- __set_bit(MAX_PRIO, array->bitmap);
+ bitmap_zero(array->prio_bitmap, MAX_PRIO);
+ /* delimiter for bitsearch */
+ __set_bit(MAX_PRIO, array->prio_bitmap);
}
- }
+ }
set_load_weight(&init_task);
#ifdef CONFIG_SMP
@@ -6815,24 +7046,24 @@ EXPORT_SYMBOL(__might_sleep);
#ifdef CONFIG_MAGIC_SYSRQ
void normalize_rt_tasks(void)
{
- struct prio_array *array;
struct task_struct *p;
unsigned long flags;
struct rq *rq;
+ int queued;
read_lock_irq(&tasklist_lock);
for_each_process(p) {
- if (!rt_task(p))
+ if (!rt_task(p) && !iso_task(p))
continue;
spin_lock_irqsave(&p->pi_lock, flags);
rq = __task_rq_lock(p);
- array = p->array;
- if (array)
+ queued = task_queued(p);
+ if (queued)
deactivate_task(p, task_rq(p));
__setscheduler(p, SCHED_NORMAL, 0);
- if (array) {
+ if (queued) {
__activate_task(p, task_rq(p));
resched_task(rq->curr);
}
Index: linux-2.6.21-ck1/Documentation/sysctl/kernel.txt
===================================================================
--- linux-2.6.21-ck1.orig/Documentation/sysctl/kernel.txt 2007-05-04 12:10:52.000000000 +1000
+++ linux-2.6.21-ck1/Documentation/sysctl/kernel.txt 2007-05-04 12:10:55.000000000 +1000
@@ -25,6 +25,9 @@ show up in /proc/sys/kernel:
- domainname
- hostname
- hotplug
+- interactive
+- iso_cpu
+- iso_period
- java-appletviewer [ binfmt_java, obsolete ]
- java-interpreter [ binfmt_java, obsolete ]
- kstack_depth_to_print [ X86 only ]
@@ -43,6 +46,7 @@ show up in /proc/sys/kernel:
- printk
- real-root-dev ==> Documentation/initrd.txt
- reboot-cmd [ SPARC only ]
+- rr_interval
- rtsig-max
- rtsig-nr
- sem
@@ -164,6 +168,40 @@ Default value is "/sbin/hotplug".
==============================================================
+interactive:
+
+The staircase-deadline cpu scheduler can be set in either purely
+forward-looking mode for absolutely rigid fairness and cpu distribution
+according to nice level, or it can allow a small per-process history
+to smooth out cpu usage perturbations common in interactive tasks by
+enabling this sysctl. While small fairness issues can arise with this
+enabled, overall fairness is usually still strongly maintained and
+starvation is never possible. Enabling this can significantly smooth
+out 3d graphics and games.
+
+Default value is 1 (enabled).
+
+==============================================================
+
+iso_cpu:
+
+This sets the percentage cpu that the unprivileged SCHED_ISO tasks can
+run effectively at realtime priority, averaged over a rolling iso_period
+seconds.
+
+Set to 80 (percent) by default.
+
+==============================================================
+
+iso_period:
+
+This sets the number of seconds over which SCHED_ISO cpu usage is averaged
+to see if it exceeds its allocated cpu bandwidth.
+
+Set to 5 (seconds) by default.
+
+==============================================================
+
l2cr: (PPC only)
This flag controls the L2 cache of G3 processor boards. If
@@ -288,6 +326,19 @@ rebooting. ???
==============================================================
+rr_interval:
+
+This is the smallest duration that any cpu process scheduling unit
+will run for. Increasing this value can increase throughput of cpu
+bound tasks substantially but at the expense of increased latencies
+overall. This value is in milliseconds and the default value chosen
+depends on the number of cpus available at scheduler initialisation
+with a minimum of 8.
+
+Valid values are from 1-5000.
+
+==============================================================
+
rtsig-max & rtsig-nr:
The file rtsig-max can be used to tune the maximum number
Index: linux-2.6.21-ck1/kernel/sysctl.c
===================================================================
--- linux-2.6.21-ck1.orig/kernel/sysctl.c 2007-05-04 12:10:52.000000000 +1000
+++ linux-2.6.21-ck1/kernel/sysctl.c 2007-05-04 12:24:21.000000000 +1000
@@ -22,6 +22,7 @@
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/slab.h>
+#include <linux/swap-prefetch.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/capability.h>
@@ -70,12 +71,17 @@ extern int suid_dumpable;
extern char core_pattern[];
extern int pid_max;
extern int min_free_kbytes;
+extern int vm_tail_largefiles;
extern int printk_ratelimit_jiffies;
extern int printk_ratelimit_burst;
extern int pid_max_min, pid_max_max;
extern int sysctl_drop_caches;
extern int percpu_pagelist_fraction;
extern int compat_log;
+extern int rr_interval;
+extern int sched_interactive;
+extern int sched_iso_cpu;
+extern int sched_iso_period;
/* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
static int maxolduid = 65535;
@@ -159,6 +165,14 @@ int sysctl_legacy_va_layout;
#endif
+/* Constants for minimum and maximum testing.
+ We use these as one-element integer vectors. */
+static int __read_mostly zero;
+static int __read_mostly one = 1;
+static int __read_mostly one_hundred = 100;
+static int __read_mostly five_thousand = 5000;
+
+
/* The default sysctl tables: */
static ctl_table root_table[] = {
@@ -499,6 +513,47 @@ static ctl_table kern_table[] = {
.mode = 0444,
.proc_handler = &proc_dointvec,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "rr_interval",
+ .data = &rr_interval,
+ .maxlen = sizeof (int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec_minmax,
+ .strategy = &sysctl_intvec,
+ .extra1 = &one,
+ .extra2 = &five_thousand,
+ },
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "interactive",
+ .data = &sched_interactive,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "iso_cpu",
+ .data = &sched_iso_cpu,
+ .maxlen = sizeof (int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec_minmax,
+ .strategy = &sysctl_intvec,
+ .extra1 = &zero,
+ .extra2 = &one_hundred,
+ },
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "iso_period",
+ .data = &sched_iso_period,
+ .maxlen = sizeof (int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec_minmax,
+ .strategy = &sysctl_intvec,
+ .extra1 = &one,
+ .extra2 = &one_hundred,
+ },
#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)
{
.ctl_name = KERN_UNKNOWN_NMI_PANIC,
@@ -607,12 +662,6 @@ static ctl_table kern_table[] = {
{ .ctl_name = 0 }
};
-/* Constants for minimum and maximum testing in vm_table.
- We use these as one-element integer vectors. */
-static int zero;
-static int one_hundred = 100;
-
-
static ctl_table vm_table[] = {
{
.ctl_name = VM_OVERCOMMIT_MEMORY,
@@ -693,16 +742,32 @@ static ctl_table vm_table[] = {
.proc_handler = &proc_dointvec,
},
{
- .ctl_name = VM_SWAPPINESS,
- .procname = "swappiness",
- .data = &vm_swappiness,
- .maxlen = sizeof(vm_swappiness),
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "mapped",
+ .data = &vm_mapped,
+ .maxlen = sizeof(vm_mapped),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &zero,
.extra2 = &one_hundred,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "hardmaplimit",
+ .data = &vm_hardmaplimit,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "tail_largefiles",
+ .data = &vm_tail_largefiles,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
#ifdef CONFIG_HUGETLB_PAGE
{
.ctl_name = VM_HUGETLB_PAGES,
@@ -859,6 +924,16 @@ static ctl_table vm_table[] = {
.extra1 = &zero,
},
#endif
+#ifdef CONFIG_SWAP_PREFETCH
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "swap_prefetch",
+ .data = &swap_prefetch,
+ .maxlen = sizeof(swap_prefetch),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+#endif
{ .ctl_name = 0 }
};
Index: linux-2.6.21-ck1/fs/pipe.c
===================================================================
--- linux-2.6.21-ck1.orig/fs/pipe.c 2007-05-04 12:10:52.000000000 +1000
+++ linux-2.6.21-ck1/fs/pipe.c 2007-05-04 12:10:54.000000000 +1000
@@ -41,12 +41,7 @@ void pipe_wait(struct pipe_inode_info *p
{
DEFINE_WAIT(wait);
- /*
- * Pipes are system-local resources, so sleeping on them
- * is considered a noninteractive wait:
- */
- prepare_to_wait(&pipe->wait, &wait,
- TASK_INTERRUPTIBLE | TASK_NONINTERACTIVE);
+ prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
if (pipe->inode)
mutex_unlock(&pipe->inode->i_mutex);
schedule();
Index: linux-2.6.21-ck1/Documentation/sched-design.txt
===================================================================
--- linux-2.6.21-ck1.orig/Documentation/sched-design.txt 2007-05-04 12:10:52.000000000 +1000
+++ linux-2.6.21-ck1/Documentation/sched-design.txt 2007-05-04 12:10:54.000000000 +1000
@@ -1,11 +1,14 @@
- Goals, Design and Implementation of the
- new ultra-scalable O(1) scheduler
+ Goals, Design and Implementation of the ultra-scalable O(1) scheduler by
+ Ingo Molnar and theStaircase Deadline cpu scheduler policy designed by
+ Con Kolivas.
- This is an edited version of an email Ingo Molnar sent to
- lkml on 4 Jan 2002. It describes the goals, design, and
- implementation of Ingo's new ultra-scalable O(1) scheduler.
- Last Updated: 18 April 2002.
+ This was originally an edited version of an email Ingo Molnar sent to
+ lkml on 4 Jan 2002. It describes the goals, design, and implementation
+ of Ingo's ultra-scalable O(1) scheduler. It now contains a description
+ of the Staircase Deadline priority scheduler that was built on this
+ design.
+ Last Updated: Fri, 4 May 2007
Goal
@@ -163,3 +166,222 @@ certain code paths and data constructs.
code is smaller than the old one.
Ingo
+
+
+Staircase Deadline cpu scheduler policy
+================================================
+
+Design summary
+==============
+
+A novel design which incorporates a foreground-background descending priority
+system (the staircase) via a bandwidth allocation matrix according to nice
+level.
+
+
+Features
+========
+
+A starvation free, strict fairness O(1) scalable design with interactivity
+as good as the above restrictions can provide. There is no interactivity
+estimator, no sleep/run measurements and only simple fixed accounting.
+The design has strict enough a design and accounting that task behaviour
+can be modelled and maximum scheduling latencies can be predicted by
+the virtual deadline mechanism that manages runqueues. The prime concern
+in this design is to maintain fairness at all costs determined by nice level,
+yet to maintain as good interactivity as can be allowed within the
+constraints of strict fairness.
+
+
+Design description
+==================
+
+SD works off the principle of providing each task a quota of runtime that it is
+allowed to run at a number of priority levels determined by its static priority
+(ie. its nice level). If the task uses up its quota it has its priority
+decremented to the next level determined by a priority matrix. Once every
+runtime quota has been consumed of every priority level, a task is queued on the
+"expired" array. When no other tasks exist with quota, the expired array is
+activated and fresh quotas are handed out. This is all done in O(1).
+
+Design details
+==============
+
+Each task keeps a record of its own entitlement of cpu time. Most of the rest of
+these details apply to non-realtime tasks as rt task management is straight
+forward.
+
+Each runqueue keeps a record of what major epoch it is up to in the
+rq->prio_rotation field which is incremented on each major epoch. It also
+keeps a record of the current prio_level for each static priority task.
+
+Each task keeps a record of what major runqueue epoch it was last running
+on in p->rotation. It also keeps a record of what priority levels it has
+already been allocated quota from during this epoch in a bitmap p->bitmap.
+
+The only tunable that determines all other details is the RR_INTERVAL. This
+is set to 8ms, and is scaled gently upwards with more cpus. This value is
+tunable via a /proc interface.
+
+All tasks are initially given a quota based on RR_INTERVAL. This is equal to
+RR_INTERVAL between nice values of -6 and 0, half that size above nice 0, and
+progressively larger for nice values from -1 to -20. This is assigned to
+p->quota and only changes with changes in nice level.
+
+As a task is first queued, it checks in recalc_task_prio to see if it has run at
+this runqueue's current priority rotation. If it has not, it will have its
+p->prio level set according to the first slot in a "priority matrix" and will be
+given a p->time_slice equal to the p->quota, and has its allocation bitmap bit
+set in p->bitmap for this prio level. It is then queued on the current active
+priority array.
+
+If a task has already been running during this major epoch, and it has
+p->time_slice left and the rq->prio_quota for the task's p->prio still
+has quota, it will be placed back on the active array, but no more quota
+will be added.
+
+If a task has been running during this major epoch, but does not have
+p->time_slice left, it will find the next lowest priority in its bitmap that it
+has not been allocated quota from. It then gets the a full quota in
+p->time_slice. It is then queued on the current active priority array at the
+newly determined lower priority.
+
+If a task has been running during this major epoch, and does not have
+any entitlement left in p->bitmap and no time_slice left, it will have its
+bitmap cleared, and be queued at its best prio again, but on the expired
+priority array.
+
+When a task is queued, it has its relevant bit set in the array->prio_bitmap.
+
+p->time_slice is stored in nanosconds and is updated via update_cpu_clock on
+schedule() and scheduler_tick. If p->time_slice is below zero then the
+recalc_task_prio is readjusted and the task rescheduled.
+
+
+Priority Matrix
+===============
+
+In order to minimise the latencies between tasks of different nice levels
+running concurrently, the dynamic priority slots where different nice levels
+are queued are dithered instead of being sequential. What this means is that
+there are 40 priority slots where a task may run during one major rotation,
+and the allocation of slots is dependant on nice level. In the
+following table, a zero represents a slot where the task may run.
+
+PRIORITY:0..................20.................39
+nice -20 0000000000000000000000000000000000000000
+nice -10 1000100010001000100010001000100010010000
+nice 0 1010101010101010101010101010101010101010
+nice 5 1011010110110101101101011011010110110110
+nice 10 1110111011101110111011101110111011101110
+nice 15 1111111011111110111111101111111011111110
+nice 19 1111111111111111111111111111111111111110
+
+As can be seen, a nice -20 task runs in every priority slot whereas a nice 19
+task only runs one slot per major rotation. This dithered table allows for the
+smallest possible maximum latencies between tasks of varying nice levels, thus
+allowing vastly different nice levels to be used.
+
+SCHED_BATCH tasks are managed slightly differently, receiving only the top
+slots from its priority bitmap giving it equal cpu as SCHED_NORMAL, but
+slightly higher latencies.
+
+
+Modelling deadline behaviour
+============================
+
+As the accounting in this design is hard and not modified by sleep average
+calculations or interactivity modifiers, it is possible to accurately
+predict the maximum latency that a task may experience under different
+conditions. This is a virtual deadline mechanism enforced by mandatory
+timeslice expiration and not outside bandwidth measurement.
+
+The maximum duration a task can run during one major epoch is determined by its
+nice value. Nice 0 tasks can run at 19 different priority levels for RR_INTERVAL
+duration during each epoch. Nice 10 tasks can run at 9 priority levels for each
+epoch, and so on. The table in the priority matrix above demonstrates how this
+is enforced.
+
+Therefore the maximum duration a runqueue epoch can take is determined by
+the number of tasks running, and their nice level. After that, the maximum
+duration it can take before a task can wait before it get scheduled is
+determined by the position of its first slot on the matrix.
+
+In the following examples, these are _worst case scenarios_ and would rarely
+occur, but can be modelled nonetheless to determine the maximum possible
+latency.
+
+So for example, if two nice 0 tasks are running, and one has just expired as
+another is activated for the first time receiving a full quota for this
+runqueue rotation, the first task will wait:
+
+nr_tasks * max_duration + nice_difference * rr_interval
+1 * 19 * RR_INTERVAL + 0 = 152ms
+
+In the presence of a nice 10 task, a nice 0 task would wait a maximum of
+1 * 10 * RR_INTERVAL + 0 = 80ms
+
+In the presence of a nice 0 task, a nice 10 task would wait a maximum of
+1 * 19 * RR_INTERVAL + 1 * RR_INTERVAL = 160ms
+
+More useful than these values, though, are the average latencies which are
+a matter of determining the average distance between priority slots of
+different nice values and multiplying them by the tasks' quota. For example
+in the presence of a nice -10 task, a nice 0 task will wait either one or
+two slots. Given that nice -10 tasks have a quota 2.5 times the RR_INTERVAL,
+this means the latencies will alternate between 2.5 and 5 RR_INTERVALs or
+20 and 40ms respectively (on uniprocessor at 1000HZ).
+
+
+Achieving interactivity
+=======================
+
+A requirement of this scheduler design was to achieve good interactivity
+despite being a completely fair deadline based design. The disadvantage of
+designs that try to achieve interactivity is that they usually do so at
+the expense of maintaining fairness. As cpu speeds increase, the requirement
+for some sort of metered unfairness towards interactive tasks becomes a less
+desirable phenomenon, but low latency and fairness remains mandatory to
+good interactive performance.
+
+This design relies on the fact that interactive tasks, by their nature,
+sleep often. Most fair scheduling designs end up penalising such tasks
+indirectly giving them less than their fair possible share because of the
+sleep, and have to use a mechanism of bonusing their priority to offset
+this based on the duration they sleep. This becomes increasingly inaccurate
+as the number of running tasks rises and more tasks spend time waiting on
+runqueues rather than sleeping, and it is impossible to tell whether the
+task that's waiting on a runqueue only intends to run for a short period and
+then sleep again after than runqueue wait. Furthermore, all such designs rely
+on a period of time to pass to accumulate some form of statistic on the task
+before deciding on how much to give them preference. The shorter this period,
+the more rapidly bursts of cpu ruin the interactive tasks behaviour. The
+longer this period, the longer it takes for interactive tasks to get low
+scheduling latencies and fair cpu.
+
+This design does not measure sleep time at all. Interactive tasks that sleep
+often will wake up having consumed very little if any of their quota for
+the current major priority rotation. The longer they have slept, the less
+likely they are to even be on the current major priority rotation. Once
+woken up, though, they get to use up a their full quota for that epoch,
+whether part of a quota remains or a full quota. Overall, however, they
+can still only run as much cpu time for that epoch as any other task of the
+same nice level. This means that two tasks behaving completely differently
+from fully cpu bound to waking/sleeping extremely frequently will still
+get the same quota of cpu, but the latter will be using its quota for that
+epoch in bursts rather than continuously. This guarantees that interactive
+tasks get the same amount of cpu as cpu bound ones.
+
+The other requirement of interactive tasks is also to obtain low latencies
+for when they are scheduled. Unlike fully cpu bound tasks and the maximum
+latencies possible described in the modelling deadline behaviour section
+above, tasks that sleep will wake up with quota available usually at the
+current runqueue's priority_level or better. This means that the most latency
+they are likely to see is one RR_INTERVAL, and often they will preempt the
+current task if it is not of a sleeping nature. This then guarantees very
+low latency for interactive tasks, and the lowest latencies for the least
+cpu bound tasks.
+
+
+Fri, 4 May 2007
+Con Kolivas <kernel@kolivas.org>
Index: linux-2.6.21-ck1/kernel/softirq.c
===================================================================
--- linux-2.6.21-ck1.orig/kernel/softirq.c 2007-05-04 12:10:52.000000000 +1000
+++ linux-2.6.21-ck1/kernel/softirq.c 2007-05-04 12:10:54.000000000 +1000
@@ -488,7 +488,7 @@ void __init softirq_init(void)
static int ksoftirqd(void * __bind_cpu)
{
- set_user_nice(current, 19);
+ set_user_nice(current, 15);
current->flags |= PF_NOFREEZE;
set_current_state(TASK_INTERRUPTIBLE);
Index: linux-2.6.21-ck1/kernel/fork.c
===================================================================
--- linux-2.6.21-ck1.orig/kernel/fork.c 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/kernel/fork.c 2007-05-04 12:24:19.000000000 +1000
@@ -1060,6 +1060,7 @@ static struct task_struct *copy_process(
p->io_context = NULL;
p->io_wait = NULL;
p->audit_context = NULL;
+ p->mutexes_held = 0;
cpuset_fork(p);
#ifdef CONFIG_NUMA
p->mempolicy = mpol_copy(p->mempolicy);
Index: linux-2.6.21-ck1/kernel/mutex.c
===================================================================
--- linux-2.6.21-ck1.orig/kernel/mutex.c 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/kernel/mutex.c 2007-05-04 12:24:19.000000000 +1000
@@ -60,6 +60,16 @@ EXPORT_SYMBOL(__mutex_init);
static void fastcall noinline __sched
__mutex_lock_slowpath(atomic_t *lock_count);
+static inline void inc_mutex_count(void)
+{
+ current->mutexes_held++;
+}
+
+static inline void dec_mutex_count(void)
+{
+ current->mutexes_held--;
+}
+
/***
* mutex_lock - acquire the mutex
* @lock: the mutex to be acquired
@@ -89,6 +99,7 @@ void inline fastcall __sched mutex_lock(
* 'unlocked' into 'locked' state.
*/
__mutex_fastpath_lock(&lock->count, __mutex_lock_slowpath);
+ inc_mutex_count();
}
EXPORT_SYMBOL(mutex_lock);
@@ -114,6 +125,7 @@ void fastcall __sched mutex_unlock(struc
* into 'unlocked' state:
*/
__mutex_fastpath_unlock(&lock->count, __mutex_unlock_slowpath);
+ dec_mutex_count();
}
EXPORT_SYMBOL(mutex_unlock);
@@ -283,9 +295,14 @@ __mutex_lock_interruptible_slowpath(atom
*/
int fastcall __sched mutex_lock_interruptible(struct mutex *lock)
{
+ int ret;
+
might_sleep();
- return __mutex_fastpath_lock_retval
+ ret = __mutex_fastpath_lock_retval
(&lock->count, __mutex_lock_interruptible_slowpath);
+ if (likely(!ret))
+ inc_mutex_count();
+ return ret;
}
EXPORT_SYMBOL(mutex_lock_interruptible);
@@ -340,8 +357,12 @@ static inline int __mutex_trylock_slowpa
*/
int fastcall __sched mutex_trylock(struct mutex *lock)
{
- return __mutex_fastpath_trylock(&lock->count,
+ int ret = __mutex_fastpath_trylock(&lock->count,
__mutex_trylock_slowpath);
+
+ if (likely(ret))
+ inc_mutex_count();
+ return ret;
}
EXPORT_SYMBOL(mutex_trylock);
Index: linux-2.6.21-ck1/block/cfq-iosched.c
===================================================================
--- linux-2.6.21-ck1.orig/block/cfq-iosched.c 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/block/cfq-iosched.c 2007-05-04 12:24:19.000000000 +1000
@@ -1258,10 +1258,12 @@ static void cfq_init_prio_data(struct cf
printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
case IOPRIO_CLASS_NONE:
/*
- * no prio set, place us in the middle of the BE classes
+ * Select class and ioprio according to policy and nice
*/
+ cfqq->ioprio_class = task_policy_ioprio_class(tsk);
cfqq->ioprio = task_nice_ioprio(tsk);
- cfqq->ioprio_class = IOPRIO_CLASS_BE;
+ if (cfqq->ioprio_class == IOPRIO_CLASS_IDLE)
+ cfq_clear_cfqq_idle_window(cfqq);
break;
case IOPRIO_CLASS_RT:
cfqq->ioprio = task_ioprio(tsk);
Index: linux-2.6.21-ck1/include/linux/ioprio.h
===================================================================
--- linux-2.6.21-ck1.orig/include/linux/ioprio.h 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/include/linux/ioprio.h 2007-05-04 12:24:19.000000000 +1000
@@ -22,7 +22,7 @@
* class, the default for any process. IDLE is the idle scheduling class, it
* is only served when no one else is using the disk.
*/
-enum {
+enum ioprio_class {
IOPRIO_CLASS_NONE,
IOPRIO_CLASS_RT,
IOPRIO_CLASS_BE,
@@ -51,8 +51,25 @@ static inline int task_ioprio(struct tas
return IOPRIO_PRIO_DATA(task->ioprio);
}
+static inline enum ioprio_class
+ task_policy_ioprio_class(struct task_struct *task)
+{
+ if (rt_task(task))
+ return IOPRIO_CLASS_RT;
+ if (idleprio_task(task))
+ return IOPRIO_CLASS_IDLE;
+ return IOPRIO_CLASS_BE;
+}
+
static inline int task_nice_ioprio(struct task_struct *task)
{
+ if (rt_task(task))
+ return (MAX_RT_PRIO - task->rt_priority) * IOPRIO_BE_NR /
+ (MAX_RT_PRIO + 1);
+ if (iso_task(task))
+ return 0;
+ if (idleprio_task(task))
+ return IOPRIO_BE_NR - 1;
return (task_nice(task) + 20) / 5;
}
Index: linux-2.6.21-ck1/Documentation/sysctl/vm.txt
===================================================================
--- linux-2.6.21-ck1.orig/Documentation/sysctl/vm.txt 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/Documentation/sysctl/vm.txt 2007-05-04 12:24:21.000000000 +1000
@@ -22,6 +22,8 @@ Currently, these files are in /proc/sys/
- dirty_background_ratio
- dirty_expire_centisecs
- dirty_writeback_centisecs
+- hardmaplimit
+- mapped
- max_map_count
- min_free_kbytes
- laptop_mode
@@ -31,12 +33,13 @@ Currently, these files are in /proc/sys/
- min_unmapped_ratio
- min_slab_ratio
- panic_on_oom
+- swap_prefetch
==============================================================
dirty_ratio, dirty_background_ratio, dirty_expire_centisecs,
dirty_writeback_centisecs, vfs_cache_pressure, laptop_mode,
-block_dump, swap_token_timeout, drop-caches:
+block_dump, swap_token_timeout, drop-caches, tail_largefiles:
See Documentation/filesystems/proc.txt
@@ -86,6 +89,27 @@ for swap because we only cluster swap da
==============================================================
+hardmaplimit:
+
+This flag makes the vm adhere to the mapped value as closely as possible
+except in the most extreme vm stress where doing so would provoke an out
+of memory condition (see mapped below).
+
+Enabled by default.
+
+==============================================================
+
+mapped:
+
+This is the percentage ram that is filled with mapped pages (applications)
+before the vm will start reclaiming mapped pages by moving them to swap.
+It is altered by the relative stress of the vm at the time so is not
+strictly adhered to to prevent provoking out of memory kills.
+
+Set to 66 by default.
+
+==============================================================
+
max_map_count:
This file contains the maximum number of memory map areas a process
@@ -205,3 +229,14 @@ rather than killing rogue processes, set
The default value is 0.
+==============================================================
+
+swap_prefetch
+
+This enables or disables the swap prefetching feature. When the virtual
+memory subsystem has been extremely idle for at least 5 seconds it will start
+copying back pages from swap into the swapcache and keep a copy in swap. In
+practice it can take many minutes before the vm is idle enough.
+
+The default value is 1.
+
Index: linux-2.6.21-ck1/include/linux/swap.h
===================================================================
--- linux-2.6.21-ck1.orig/include/linux/swap.h 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/include/linux/swap.h 2007-05-04 12:24:20.000000000 +1000
@@ -180,6 +180,7 @@ extern unsigned int nr_free_pagecache_pa
/* linux/mm/swap.c */
extern void FASTCALL(lru_cache_add(struct page *));
extern void FASTCALL(lru_cache_add_active(struct page *));
+extern void FASTCALL(lru_cache_add_tail(struct page *));
extern void FASTCALL(activate_page(struct page *));
extern void FASTCALL(mark_page_accessed(struct page *));
extern void lru_add_drain(void);
@@ -188,9 +189,11 @@ extern int rotate_reclaimable_page(struc
extern void swap_setup(void);
/* linux/mm/vmscan.c */
-extern unsigned long try_to_free_pages(struct zone **, gfp_t);
+extern unsigned long try_to_free_pages(struct zone **, gfp_t,
+ struct task_struct *p);
extern unsigned long shrink_all_memory(unsigned long nr_pages);
-extern int vm_swappiness;
+extern int vm_mapped;
+extern int vm_hardmaplimit;
extern int remove_mapping(struct address_space *mapping, struct page *page);
extern long vm_total_pages;
@@ -237,6 +240,7 @@ extern void free_pages_and_swap_cache(st
extern struct page * lookup_swap_cache(swp_entry_t);
extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
unsigned long addr);
+extern int add_to_swap_cache(struct page *page, swp_entry_t entry);
/* linux/mm/swapfile.c */
extern long total_swap_pages;
extern unsigned int nr_swapfiles;
Index: linux-2.6.21-ck1/init/Kconfig
===================================================================
--- linux-2.6.21-ck1.orig/init/Kconfig 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/init/Kconfig 2007-05-04 12:24:20.000000000 +1000
@@ -101,6 +101,28 @@ config SWAP
used to provide more virtual memory than the actual RAM present
in your computer. If unsure say Y.
+config SWAP_PREFETCH
+ bool "Support for prefetching swapped memory"
+ depends on SWAP
+ default y
+ ---help---
+ This option will allow the kernel to prefetch swapped memory pages
+ when idle. The pages will be kept on both swap and in swap_cache
+ thus avoiding the need for further I/O if either ram or swap space
+ is required.
+
+ What this will do on workstations is slowly bring back applications
+ that have swapped out after memory intensive workloads back into
+ physical ram if you have free ram at a later stage and the machine
+ is relatively idle. This means that when you come back to your
+ computer after leaving it idle for a while, applications will come
+ to life faster. Note that your swap usage will appear to increase
+ but these are cached pages, can be dropped freely by the vm, and it
+ should stabilise around 50% swap usage maximum.
+
+ Workstations and multiuser workstation servers will most likely want
+ to say Y.
+
config SYSVIPC
bool "System V IPC"
---help---
Index: linux-2.6.21-ck1/mm/Makefile
===================================================================
--- linux-2.6.21-ck1.orig/mm/Makefile 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/mm/Makefile 2007-05-04 12:24:20.000000000 +1000
@@ -17,6 +17,7 @@ ifeq ($(CONFIG_MMU)$(CONFIG_BLOCK),yy)
obj-y += bounce.o
endif
obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o thrash.o
+obj-$(CONFIG_SWAP_PREFETCH) += swap_prefetch.o
obj-$(CONFIG_HUGETLBFS) += hugetlb.o
obj-$(CONFIG_NUMA) += mempolicy.o
obj-$(CONFIG_SPARSEMEM) += sparse.o
Index: linux-2.6.21-ck1/mm/swap.c
===================================================================
--- linux-2.6.21-ck1.orig/mm/swap.c 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/mm/swap.c 2007-05-04 12:24:21.000000000 +1000
@@ -17,6 +17,7 @@
#include <linux/sched.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
+#include <linux/swap-prefetch.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
@@ -176,6 +177,7 @@ EXPORT_SYMBOL(mark_page_accessed);
*/
static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
+static DEFINE_PER_CPU(struct pagevec, lru_add_tail_pvecs) = { 0, };
void fastcall lru_cache_add(struct page *page)
{
@@ -197,6 +199,31 @@ void fastcall lru_cache_add_active(struc
put_cpu_var(lru_add_active_pvecs);
}
+static void __pagevec_lru_add_tail(struct pagevec *pvec)
+{
+ int i;
+ struct zone *zone = NULL;
+
+ for (i = 0; i < pagevec_count(pvec); i++) {
+ struct page *page = pvec->pages[i];
+ struct zone *pagezone = page_zone(page);
+
+ if (pagezone != zone) {
+ if (zone)
+ spin_unlock_irq(&zone->lru_lock);
+ zone = pagezone;
+ spin_lock_irq(&zone->lru_lock);
+ }
+ BUG_ON(PageLRU(page));
+ SetPageLRU(page);
+ add_page_to_inactive_list_tail(zone, page);
+ }
+ if (zone)
+ spin_unlock_irq(&zone->lru_lock);
+ release_pages(pvec->pages, pvec->nr, pvec->cold);
+ pagevec_reinit(pvec);
+}
+
static void __lru_add_drain(int cpu)
{
struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);
@@ -207,6 +234,9 @@ static void __lru_add_drain(int cpu)
pvec = &per_cpu(lru_add_active_pvecs, cpu);
if (pagevec_count(pvec))
__pagevec_lru_add_active(pvec);
+ pvec = &per_cpu(lru_add_tail_pvecs, cpu);
+ if (pagevec_count(pvec))
+ __pagevec_lru_add_tail(pvec);
}
void lru_add_drain(void)
@@ -403,6 +433,20 @@ void __pagevec_lru_add_active(struct pag
}
/*
+ * Function used uniquely to put pages back to the lru at the end of the
+ * inactive list to preserve the lru order.
+ */
+void fastcall lru_cache_add_tail(struct page *page)
+{
+ struct pagevec *pvec = &get_cpu_var(lru_add_tail_pvecs);
+
+ page_cache_get(page);
+ if (!pagevec_add(pvec, page))
+ __pagevec_lru_add_tail(pvec);
+ put_cpu_var(lru_add_pvecs);
+}
+
+/*
* Try to drop buffers from the pages in a pagevec
*/
void pagevec_strip(struct pagevec *pvec)
@@ -514,6 +558,9 @@ void __init swap_setup(void)
* Right now other parts of the system means that we
* _really_ don't want to cluster much more
*/
+
+ prepare_swap_prefetch();
+
#ifdef CONFIG_HOTPLUG_CPU
hotcpu_notifier(cpu_swap_callback, 0);
#endif
Index: linux-2.6.21-ck1/mm/swap_prefetch.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.21-ck1/mm/swap_prefetch.c 2007-05-04 12:24:20.000000000 +1000
@@ -0,0 +1,581 @@
+/*
+ * linux/mm/swap_prefetch.c
+ *
+ * Copyright (C) 2005-2006 Con Kolivas
+ *
+ * Written by Con Kolivas <kernel@kolivas.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/swap-prefetch.h>
+#include <linux/ioprio.h>
+#include <linux/kthread.h>
+#include <linux/pagemap.h>
+#include <linux/syscalls.h>
+#include <linux/writeback.h>
+#include <linux/vmstat.h>
+#include <linux/freezer.h>
+
+/*
+ * Time to delay prefetching if vm is busy or prefetching unsuccessful. There
+ * needs to be at least this duration of idle time meaning in practice it can
+ * be much longer
+ */
+#define PREFETCH_DELAY (HZ * 5)
+
+/* sysctl - enable/disable swap prefetching */
+int swap_prefetch __read_mostly = 1;
+
+struct swapped_root {
+ unsigned long busy; /* vm busy */
+ spinlock_t lock; /* protects all data */
+ struct list_head list; /* MRU list of swapped pages */
+ struct radix_tree_root swap_tree; /* Lookup tree of pages */
+ unsigned int count; /* Number of entries */
+ unsigned int maxcount; /* Maximum entries allowed */
+ struct kmem_cache *cache; /* Of struct swapped_entry */
+};
+
+static struct swapped_root swapped = {
+ .lock = SPIN_LOCK_UNLOCKED,
+ .list = LIST_HEAD_INIT(swapped.list),
+ .swap_tree = RADIX_TREE_INIT(GFP_ATOMIC),
+};
+
+static struct task_struct *kprefetchd_task;
+
+/*
+ * We check to see no part of the vm is busy. If it is this will interrupt
+ * trickle_swap and wait another PREFETCH_DELAY. Purposefully racy.
+ */
+inline void delay_swap_prefetch(void)
+{
+ if (!test_bit(0, &swapped.busy))
+ __set_bit(0, &swapped.busy);
+}
+
+/*
+ * Drop behind accounting which keeps a list of the most recently used swap
+ * entries.
+ */
+void add_to_swapped_list(struct page *page)
+{
+ struct swapped_entry *entry;
+ unsigned long index, flags;
+ int wakeup;
+
+ if (!swap_prefetch)
+ return;
+
+ wakeup = 0;
+
+ spin_lock_irqsave(&swapped.lock, flags);
+ if (swapped.count >= swapped.maxcount) {
+ /*
+ * We limit the number of entries to 2/3 of physical ram.
+ * Once the number of entries exceeds this we start removing
+ * the least recently used entries.
+ */
+ entry = list_entry(swapped.list.next,
+ struct swapped_entry, swapped_list);
+ radix_tree_delete(&swapped.swap_tree, entry->swp_entry.val);
+ list_del(&entry->swapped_list);
+ swapped.count--;
+ } else {
+ entry = kmem_cache_alloc(swapped.cache, GFP_ATOMIC);
+ if (unlikely(!entry))
+ /* bad, can't allocate more mem */
+ goto out_locked;
+ }
+
+ index = page_private(page);
+ entry->swp_entry.val = index;
+ /*
+ * On numa we need to store the node id to ensure that we prefetch to
+ * the same node it came from.
+ */
+ store_swap_entry_node(entry, page);
+
+ if (likely(!radix_tree_insert(&swapped.swap_tree, index, entry))) {
+ /*
+ * If this is the first entry, kprefetchd needs to be
+ * (re)started.
+ */
+ if (!swapped.count)
+ wakeup = 1;
+ list_add(&entry->swapped_list, &swapped.list);
+ swapped.count++;
+ }
+
+out_locked:
+ spin_unlock_irqrestore(&swapped.lock, flags);
+
+ /* Do the wakeup outside the lock to shorten lock hold time. */
+ if (wakeup)
+ wake_up_process(kprefetchd_task);
+
+ return;
+}
+
+/*
+ * Removes entries from the swapped_list. The radix tree allows us to quickly
+ * look up the entry from the index without having to iterate over the whole
+ * list.
+ */
+void remove_from_swapped_list(const unsigned long index)
+{
+ struct swapped_entry *entry;
+ unsigned long flags;
+
+ if (list_empty(&swapped.list))
+ return;
+
+ spin_lock_irqsave(&swapped.lock, flags);
+ entry = radix_tree_delete(&swapped.swap_tree, index);
+ if (likely(entry)) {
+ list_del_init(&entry->swapped_list);
+ swapped.count--;
+ kmem_cache_free(swapped.cache, entry);
+ }
+ spin_unlock_irqrestore(&swapped.lock, flags);
+}
+
+enum trickle_return {
+ TRICKLE_SUCCESS,
+ TRICKLE_FAILED,
+ TRICKLE_DELAY,
+};
+
+struct node_stats {
+ unsigned long last_free;
+ /* Free ram after a cycle of prefetching */
+ unsigned long current_free;
+ /* Free ram on this cycle of checking prefetch_suitable */
+ unsigned long prefetch_watermark;
+ /* Maximum amount we will prefetch to */
+ unsigned long highfree[MAX_NR_ZONES];
+ /* The amount of free ram before we start prefetching */
+ unsigned long lowfree[MAX_NR_ZONES];
+ /* The amount of free ram where we will stop prefetching */
+ unsigned long *pointfree[MAX_NR_ZONES];
+ /* highfree or lowfree depending on whether we've hit a watermark */
+};
+
+/*
+ * prefetch_stats stores the free ram data of each node and this is used to
+ * determine if a node is suitable for prefetching into.
+ */
+struct prefetch_stats {
+ nodemask_t prefetch_nodes;
+ /* Which nodes are currently suited to prefetching */
+ unsigned long prefetched_pages;
+ /* Total pages we've prefetched on this wakeup of kprefetchd */
+ struct node_stats node[MAX_NUMNODES];
+};
+
+static struct prefetch_stats sp_stat;
+
+/*
+ * This tries to read a swp_entry_t into swap cache for swap prefetching.
+ * If it returns TRICKLE_DELAY we should delay further prefetching.
+ */
+static enum trickle_return trickle_swap_cache_async(const swp_entry_t entry,
+ const int node)
+{
+ enum trickle_return ret = TRICKLE_FAILED;
+ struct page *page;
+
+ read_lock_irq(&swapper_space.tree_lock);
+ /* Entry may already exist */
+ page = radix_tree_lookup(&swapper_space.page_tree, entry.val);
+ read_unlock_irq(&swapper_space.tree_lock);
+ if (page) {
+ remove_from_swapped_list(entry.val);
+ goto out;
+ }
+
+ /*
+ * Get a new page to read from swap. We have already checked the
+ * watermarks so __alloc_pages will not call on reclaim.
+ */
+ page = alloc_pages_node(node, GFP_HIGHUSER & ~__GFP_WAIT, 0);
+ if (unlikely(!page)) {
+ ret = TRICKLE_DELAY;
+ goto out;
+ }
+
+ if (add_to_swap_cache(page, entry)) {
+ /* Failed to add to swap cache */
+ goto out_release;
+ }
+
+ /* Add them to the tail of the inactive list to preserve LRU order */
+ lru_cache_add_tail(page);
+ if (unlikely(swap_readpage(NULL, page))) {
+ ret = TRICKLE_DELAY;
+ goto out_release;
+ }
+
+ sp_stat.prefetched_pages++;
+ sp_stat.node[node].last_free--;
+
+ ret = TRICKLE_SUCCESS;
+out_release:
+ page_cache_release(page);
+out:
+ return ret;
+}
+
+static void clear_last_prefetch_free(void)
+{
+ int node;
+
+ /*
+ * Reset the nodes suitable for prefetching to all nodes. We could
+ * update the data to take into account memory hotplug if desired..
+ */
+ sp_stat.prefetch_nodes = node_online_map;
+ for_each_node_mask(node, sp_stat.prefetch_nodes) {
+ struct node_stats *ns = &sp_stat.node[node];
+
+ ns->last_free = 0;
+ }
+}
+
+static void clear_current_prefetch_free(void)
+{
+ int node;
+
+ sp_stat.prefetch_nodes = node_online_map;
+ for_each_node_mask(node, sp_stat.prefetch_nodes) {
+ struct node_stats *ns = &sp_stat.node[node];
+
+ ns->current_free = 0;
+ }
+}
+
+/*
+ * This updates the high and low watermarks of amount of free ram in each
+ * node used to start and stop prefetching. We prefetch from pages_high * 4
+ * down to pages_high * 3.
+ */
+static void examine_free_limits(void)
+{
+ struct zone *z;
+
+ for_each_zone(z) {
+ struct node_stats *ns;
+ int idx;
+
+ if (!populated_zone(z))
+ continue;
+
+ ns = &sp_stat.node[z->zone_pgdat->node_id];
+ idx = zone_idx(z);
+ ns->lowfree[idx] = z->pages_high * 3;
+ ns->highfree[idx] = ns->lowfree[idx] + z->pages_high;
+
+ if (zone_page_state(z, NR_FREE_PAGES) > ns->highfree[idx]) {
+ /*
+ * We've gotten above the high watermark of free pages
+ * so we can start prefetching till we get to the low
+ * watermark.
+ */
+ ns->pointfree[idx] = &ns->lowfree[idx];
+ }
+ }
+}
+
+/*
+ * We want to be absolutely certain it's ok to start prefetching.
+ */
+static int prefetch_suitable(void)
+{
+ unsigned long limit;
+ struct zone *z;
+ int node, ret = 0, test_pagestate = 0;
+
+ /* Purposefully racy */
+ if (test_bit(0, &swapped.busy)) {
+ __clear_bit(0, &swapped.busy);
+ goto out;
+ }
+
+ /*
+ * get_page_state and above_background_load are expensive so we only
+ * perform them every SWAP_CLUSTER_MAX prefetched_pages.
+ * We test to see if we're above_background_load as disk activity
+ * even at low priority can cause interrupt induced scheduling
+ * latencies.
+ */
+ if (!(sp_stat.prefetched_pages % SWAP_CLUSTER_MAX)) {
+ if (above_background_load())
+ goto out;
+ test_pagestate = 1;
+ }
+
+ clear_current_prefetch_free();
+
+ /*
+ * Have some hysteresis between where page reclaiming and prefetching
+ * will occur to prevent ping-ponging between them.
+ */
+ for_each_zone(z) {
+ struct node_stats *ns;
+ unsigned long free;
+ int idx;
+
+ if (!populated_zone(z))
+ continue;
+
+ node = z->zone_pgdat->node_id;
+ ns = &sp_stat.node[node];
+ idx = zone_idx(z);
+
+ free = zone_page_state(z, NR_FREE_PAGES);
+ if (free < *ns->pointfree[idx]) {
+ /*
+ * Free pages have dropped below the low watermark so
+ * we won't start prefetching again till we hit the
+ * high watermark of free pages.
+ */
+ ns->pointfree[idx] = &ns->highfree[idx];
+ node_clear(node, sp_stat.prefetch_nodes);
+ continue;
+ }
+ ns->current_free += free;
+ }
+
+ /*
+ * We iterate over each node testing to see if it is suitable for
+ * prefetching and clear the nodemask if it is not.
+ */
+ for_each_node_mask(node, sp_stat.prefetch_nodes) {
+ struct node_stats *ns = &sp_stat.node[node];
+
+ /*
+ * We check to see that pages are not being allocated
+ * elsewhere at any significant rate implying any
+ * degree of memory pressure (eg during file reads)
+ */
+ if (ns->last_free) {
+ if (ns->current_free + SWAP_CLUSTER_MAX <
+ ns->last_free) {
+ ns->last_free = ns->current_free;
+ node_clear(node,
+ sp_stat.prefetch_nodes);
+ continue;
+ }
+ } else
+ ns->last_free = ns->current_free;
+
+ if (!test_pagestate)
+ continue;
+
+ /* We shouldn't prefetch when we are doing writeback */
+ if (node_page_state(node, NR_WRITEBACK)) {
+ node_clear(node, sp_stat.prefetch_nodes);
+ continue;
+ }
+
+ /*
+ * >2/3 of the ram on this node is mapped, slab, swapcache or
+ * dirty, we need to leave some free for pagecache.
+ */
+ limit = node_page_state(node, NR_FILE_PAGES);
+ limit += node_page_state(node, NR_SLAB_RECLAIMABLE);
+ limit += node_page_state(node, NR_SLAB_UNRECLAIMABLE);
+ limit += node_page_state(node, NR_FILE_DIRTY);
+ limit += node_page_state(node, NR_UNSTABLE_NFS);
+ limit += total_swapcache_pages;
+ if (limit > ns->prefetch_watermark) {
+ node_clear(node, sp_stat.prefetch_nodes);
+ continue;
+ }
+ }
+
+ if (nodes_empty(sp_stat.prefetch_nodes))
+ goto out;
+
+ /* Survived all that? Hooray we can prefetch! */
+ ret = 1;
+out:
+ return ret;
+}
+
+/*
+ * Get previous swapped entry when iterating over all entries. swapped.lock
+ * should be held and we should already ensure that entry exists.
+ */
+static inline struct swapped_entry *prev_swapped_entry
+ (struct swapped_entry *entry)
+{
+ return list_entry(entry->swapped_list.prev->prev,
+ struct swapped_entry, swapped_list);
+}
+
+/*
+ * trickle_swap is the main function that initiates the swap prefetching. It
+ * first checks to see if the busy flag is set, and does not prefetch if it
+ * is, as the flag implied we are low on memory or swapping in currently.
+ * Otherwise it runs until prefetch_suitable fails which occurs when the
+ * vm is busy, we prefetch to the watermark, or the list is empty or we have
+ * iterated over all entries
+ */
+static enum trickle_return trickle_swap(void)
+{
+ enum trickle_return ret = TRICKLE_DELAY;
+ struct swapped_entry *entry;
+ unsigned long flags;
+
+ /*
+ * If laptop_mode is enabled don't prefetch to avoid hard drives
+ * doing unnecessary spin-ups
+ */
+ if (!swap_prefetch || laptop_mode)
+ return ret;
+
+ examine_free_limits();
+ entry = NULL;
+
+ for ( ; ; ) {
+ swp_entry_t swp_entry;
+ int node;
+
+ if (!prefetch_suitable())
+ break;
+
+ spin_lock_irqsave(&swapped.lock, flags);
+ if (list_empty(&swapped.list)) {
+ ret = TRICKLE_FAILED;
+ spin_unlock_irqrestore(&swapped.lock, flags);
+ break;
+ }
+
+ if (!entry) {
+ /*
+ * This sets the entry for the first iteration. It
+ * also is a safeguard against the entry disappearing
+ * while the lock is not held.
+ */
+ entry = list_entry(swapped.list.prev,
+ struct swapped_entry, swapped_list);
+ } else if (entry->swapped_list.prev == swapped.list.next) {
+ /*
+ * If we have iterated over all entries and there are
+ * still entries that weren't swapped out there may
+ * be a reason we could not swap them back in so
+ * delay attempting further prefetching.
+ */
+ spin_unlock_irqrestore(&swapped.lock, flags);
+ break;
+ }
+
+ node = get_swap_entry_node(entry);
+ if (!node_isset(node, sp_stat.prefetch_nodes)) {
+ /*
+ * We found an entry that belongs to a node that is
+ * not suitable for prefetching so skip it.
+ */
+ entry = prev_swapped_entry(entry);
+ spin_unlock_irqrestore(&swapped.lock, flags);
+ continue;
+ }
+ swp_entry = entry->swp_entry;
+ entry = prev_swapped_entry(entry);
+ spin_unlock_irqrestore(&swapped.lock, flags);
+
+ if (trickle_swap_cache_async(swp_entry, node) == TRICKLE_DELAY)
+ break;
+ }
+
+ if (sp_stat.prefetched_pages) {
+ lru_add_drain();
+ sp_stat.prefetched_pages = 0;
+ }
+ return ret;
+}
+
+static int kprefetchd(void *__unused)
+{
+ struct sched_param param = { .sched_priority = 0 };
+
+ sched_setscheduler(current, SCHED_BATCH, &param);
+ set_user_nice(current, 19);
+ /* Set ioprio to lowest if supported by i/o scheduler */
+ sys_ioprio_set(IOPRIO_WHO_PROCESS, 0, IOPRIO_CLASS_IDLE);
+
+ /* kprefetchd has nothing to do until it is woken up the first time */
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule();
+
+ do {
+ try_to_freeze();
+
+ /*
+ * TRICKLE_FAILED implies no entries left - we do not schedule
+ * a wakeup, and further delay the next one.
+ */
+ if (trickle_swap() == TRICKLE_FAILED) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule();
+ }
+ clear_last_prefetch_free();
+ schedule_timeout_interruptible(PREFETCH_DELAY);
+ } while (!kthread_should_stop());
+
+ return 0;
+}
+
+/*
+ * Create kmem cache for swapped entries
+ */
+void __init prepare_swap_prefetch(void)
+{
+ struct zone *zone;
+
+ swapped.cache = kmem_cache_create("swapped_entry",
+ sizeof(struct swapped_entry), 0, SLAB_PANIC, NULL, NULL);
+
+ /*
+ * Set max number of entries to 2/3 the size of physical ram as we
+ * only ever prefetch to consume 2/3 of the ram.
+ */
+ swapped.maxcount = nr_free_pagecache_pages() / 3 * 2;
+
+ for_each_zone(zone) {
+ unsigned long present;
+ struct node_stats *ns;
+ int idx;
+
+ present = zone->present_pages;
+ if (!present)
+ continue;
+
+ ns = &sp_stat.node[zone->zone_pgdat->node_id];
+ ns->prefetch_watermark += present / 3 * 2;
+ idx = zone_idx(zone);
+ ns->pointfree[idx] = &ns->highfree[idx];
+ }
+}
+
+static int __init kprefetchd_init(void)
+{
+ kprefetchd_task = kthread_run(kprefetchd, NULL, "kprefetchd");
+
+ return 0;
+}
+
+static void __exit kprefetchd_exit(void)
+{
+ kthread_stop(kprefetchd_task);
+}
+
+module_init(kprefetchd_init);
+module_exit(kprefetchd_exit);
Index: linux-2.6.21-ck1/mm/swap_state.c
===================================================================
--- linux-2.6.21-ck1.orig/mm/swap_state.c 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/mm/swap_state.c 2007-05-04 12:24:20.000000000 +1000
@@ -10,6 +10,7 @@
#include <linux/mm.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
+#include <linux/swap-prefetch.h>
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/buffer_head.h>
@@ -82,6 +83,7 @@ static int __add_to_swap_cache(struct pa
error = radix_tree_insert(&swapper_space.page_tree,
entry.val, page);
if (!error) {
+ remove_from_swapped_list(entry.val);
page_cache_get(page);
SetPageLocked(page);
SetPageSwapCache(page);
@@ -95,11 +97,12 @@ static int __add_to_swap_cache(struct pa
return error;
}
-static int add_to_swap_cache(struct page *page, swp_entry_t entry)
+int add_to_swap_cache(struct page *page, swp_entry_t entry)
{
int error;
if (!swap_duplicate(entry)) {
+ remove_from_swapped_list(entry.val);
INC_CACHE_INFO(noent_race);
return -ENOENT;
}
@@ -148,6 +151,9 @@ int add_to_swap(struct page * page, gfp_
swp_entry_t entry;
int err;
+ /* Swap prefetching is delayed if we're swapping pages */
+ delay_swap_prefetch();
+
BUG_ON(!PageLocked(page));
for (;;) {
@@ -320,6 +326,9 @@ struct page *read_swap_cache_async(swp_e
struct page *found_page, *new_page = NULL;
int err;
+ /* Swap prefetching is delayed if we're already reading from swap */
+ delay_swap_prefetch();
+
do {
/*
* First check the swap cache. Since this is normally
Index: linux-2.6.21-ck1/mm/vmscan.c
===================================================================
--- linux-2.6.21-ck1.orig/mm/vmscan.c 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/mm/vmscan.c 2007-05-04 12:24:21.000000000 +1000
@@ -16,6 +16,7 @@
#include <linux/slab.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
+#include <linux/swap-prefetch.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/highmem.h>
@@ -36,6 +37,7 @@
#include <linux/rwsem.h>
#include <linux/delay.h>
#include <linux/kthread.h>
+#include <linux/timer.h>
#include <linux/freezer.h>
#include <asm/tlbflush.h>
@@ -63,7 +65,7 @@ struct scan_control {
* whole list at once. */
int swap_cluster_max;
- int swappiness;
+ int mapped;
int all_unreclaimable;
};
@@ -110,9 +112,10 @@ struct shrinker {
#endif
/*
- * From 0 .. 100. Higher means more swappy.
+ * From 0 .. 100. Lower means more swappy.
*/
-int vm_swappiness = 60;
+int vm_mapped __read_mostly = 66;
+int vm_hardmaplimit __read_mostly = 1;
long vm_total_pages; /* The total number of pages which the VM controls */
static LIST_HEAD(shrinker_list);
@@ -424,6 +427,7 @@ int remove_mapping(struct address_space
if (PageSwapCache(page)) {
swp_entry_t swap = { .val = page_private(page) };
+ add_to_swapped_list(page);
__delete_from_swap_cache(page);
write_unlock_irq(&mapping->tree_lock);
swap_free(swap);
@@ -807,10 +811,14 @@ static void shrink_active_list(unsigned
* The distress ratio is important - we don't want to start
* going oom.
*
- * A 100% value of vm_swappiness overrides this algorithm
- * altogether.
+ * This distress value is ignored if we apply a hardmaplimit except
+ * in extreme distress.
+ *
+ * A 0% value of vm_mapped overrides this algorithm altogether.
*/
- swap_tendency = mapped_ratio / 2 + distress + sc->swappiness;
+ swap_tendency = mapped_ratio * 100 / (sc->mapped + 1);
+ if (!vm_hardmaplimit || distress == 100)
+ swap_tendency += distress;
/*
* Now use this metric to decide whether to start moving mapped
@@ -959,6 +967,41 @@ static unsigned long shrink_zone(int pri
}
/*
+ * Helper functions to adjust nice level of kswapd, based on the priority of
+ * the task (p) that called it. If it is already higher priority we do not
+ * demote its nice level since it is still working on behalf of a higher
+ * priority task. With kernel threads we leave it at nice 0.
+ *
+ * We don't ever run kswapd real time, so if a real time task calls kswapd we
+ * set it to highest SCHED_NORMAL priority.
+ */
+static int effective_sc_prio(struct task_struct *p)
+{
+ if (likely(p->mm)) {
+ if (rt_task(p))
+ return -20;
+ if (idleprio_task(p))
+ return 19;
+ return task_nice(p);
+ }
+ return 0;
+}
+
+static void set_kswapd_nice(struct task_struct *kswapd, struct task_struct *p,
+ int active)
+{
+ long nice = effective_sc_prio(p);
+
+ if (task_nice(kswapd) > nice || !active)
+ set_user_nice(kswapd, nice);
+}
+
+static int sc_priority(struct task_struct *p)
+{
+ return (DEF_PRIORITY + (DEF_PRIORITY * effective_sc_prio(p) / 40));
+}
+
+/*
* This is the direct reclaim path, for page-allocating processes. We only
* try to reclaim pages from zones which will satisfy the caller's allocation
* request.
@@ -1015,7 +1058,8 @@ static unsigned long shrink_zones(int pr
* holds filesystem locks which prevent writeout this might not work, and the
* allocation attempt will fail.
*/
-unsigned long try_to_free_pages(struct zone **zones, gfp_t gfp_mask)
+unsigned long try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
+ struct task_struct *p)
{
int priority;
int ret = 0;
@@ -1023,15 +1067,20 @@ unsigned long try_to_free_pages(struct z
unsigned long nr_reclaimed = 0;
struct reclaim_state *reclaim_state = current->reclaim_state;
unsigned long lru_pages = 0;
- int i;
+ int i, scan_priority = DEF_PRIORITY;
struct scan_control sc = {
.gfp_mask = gfp_mask,
.may_writepage = !laptop_mode,
.swap_cluster_max = SWAP_CLUSTER_MAX,
.may_swap = 1,
- .swappiness = vm_swappiness,
+ .mapped = vm_mapped,
};
+ if (p)
+ scan_priority = sc_priority(p);
+
+ delay_swap_prefetch();
+
count_vm_event(ALLOCSTALL);
for (i = 0; zones[i] != NULL; i++) {
@@ -1044,7 +1093,7 @@ unsigned long try_to_free_pages(struct z
+ zone_page_state(zone, NR_INACTIVE);
}
- for (priority = DEF_PRIORITY; priority >= 0; priority--) {
+ for (priority = scan_priority; priority >= 0; priority--) {
sc.nr_scanned = 0;
if (!priority)
disable_swap_token();
@@ -1074,7 +1123,7 @@ unsigned long try_to_free_pages(struct z
}
/* Take a nap, wait for some writeback to complete */
- if (sc.nr_scanned && priority < DEF_PRIORITY - 2)
+ if (sc.nr_scanned && priority < scan_priority - 2)
congestion_wait(WRITE, HZ/10);
}
/* top priority shrink_caches still had more to do? don't OOM, then */
@@ -1124,9 +1173,9 @@ out:
*/
static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
{
- int all_zones_ok;
+ int all_zones_ok = 0;
int priority;
- int i;
+ int i, scan_priority;
unsigned long total_scanned;
unsigned long nr_reclaimed;
struct reclaim_state *reclaim_state = current->reclaim_state;
@@ -1134,7 +1183,7 @@ static unsigned long balance_pgdat(pg_da
.gfp_mask = GFP_KERNEL,
.may_swap = 1,
.swap_cluster_max = SWAP_CLUSTER_MAX,
- .swappiness = vm_swappiness,
+ .mapped = vm_mapped,
};
/*
* temp_priority is used to remember the scanning priority at which
@@ -1142,6 +1191,8 @@ static unsigned long balance_pgdat(pg_da
*/
int temp_priority[MAX_NR_ZONES];
+ scan_priority = sc_priority(pgdat->kswapd);
+
loop_again:
total_scanned = 0;
nr_reclaimed = 0;
@@ -1149,9 +1200,9 @@ loop_again:
count_vm_event(PAGEOUTRUN);
for (i = 0; i < pgdat->nr_zones; i++)
- temp_priority[i] = DEF_PRIORITY;
+ temp_priority[i] = scan_priority;
- for (priority = DEF_PRIORITY; priority >= 0; priority--) {
+ for (priority = scan_priority; priority >= 0; priority--) {
int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */
unsigned long lru_pages = 0;
@@ -1167,15 +1218,22 @@ loop_again:
*/
for (i = pgdat->nr_zones - 1; i >= 0; i--) {
struct zone *zone = pgdat->node_zones + i;
+ unsigned long watermark;
if (!populated_zone(zone))
continue;
- if (zone->all_unreclaimable && priority != DEF_PRIORITY)
+ if (zone->all_unreclaimable && priority != scan_priority)
continue;
- if (!zone_watermark_ok(zone, order, zone->pages_high,
- 0, 0)) {
+ /*
+ * The watermark is relaxed depending on the
+ * level of "priority" till it drops to
+ * pages_high.
+ */
+ watermark = zone->pages_high + (zone->pages_high *
+ priority / scan_priority);
+ if (!zone_watermark_ok(zone, order, watermark, 0, 0)) {
end_zone = i;
break;
}
@@ -1202,14 +1260,18 @@ loop_again:
for (i = 0; i <= end_zone; i++) {
struct zone *zone = pgdat->node_zones + i;
int nr_slab;
+ unsigned long watermark;
if (!populated_zone(zone))
continue;
- if (zone->all_unreclaimable && priority != DEF_PRIORITY)
+ if (zone->all_unreclaimable && priority != scan_priority)
continue;
- if (!zone_watermark_ok(zone, order, zone->pages_high,
+ watermark = zone->pages_high + (zone->pages_high *
+ priority / scan_priority);
+
+ if (!zone_watermark_ok(zone, order, watermark,
end_zone, 0))
all_zones_ok = 0;
temp_priority[i] = priority;
@@ -1242,7 +1304,7 @@ loop_again:
* OK, kswapd is getting into trouble. Take a nap, then take
* another pass across the zones.
*/
- if (total_scanned && priority < DEF_PRIORITY - 2)
+ if (total_scanned && priority < scan_priority - 2)
congestion_wait(WRITE, HZ/10);
/*
@@ -1276,6 +1338,8 @@ out:
return nr_reclaimed;
}
+#define WT_EXPIRY (HZ * 5) /* Time to wakeup watermark_timer */
+
/*
* The background pageout daemon, started as a kernel thread
* from the init process.
@@ -1325,6 +1389,8 @@ static int kswapd(void *p)
try_to_freeze();
+ /* kswapd has been busy so delay watermark_timer */
+ mod_timer(&pgdat->watermark_timer, jiffies + WT_EXPIRY);
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
new_order = pgdat->kswapd_max_order;
pgdat->kswapd_max_order = 0;
@@ -1335,6 +1401,7 @@ static int kswapd(void *p)
*/
order = new_order;
} else {
+ set_user_nice(tsk, 0);
schedule();
order = pgdat->kswapd_max_order;
}
@@ -1348,9 +1415,10 @@ static int kswapd(void *p)
/*
* A zone is low on free memory, so wake its kswapd task to service it.
*/
-void wakeup_kswapd(struct zone *zone, int order)
+void wakeup_kswapd(struct zone *zone, int order, struct task_struct *p)
{
pg_data_t *pgdat;
+ int active;
if (!populated_zone(zone))
return;
@@ -1362,7 +1430,9 @@ void wakeup_kswapd(struct zone *zone, in
pgdat->kswapd_max_order = order;
if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
return;
- if (!waitqueue_active(&pgdat->kswapd_wait))
+ active = waitqueue_active(&pgdat->kswapd_wait);
+ set_kswapd_nice(pgdat->kswapd, p, active);
+ if (!active)
return;
wake_up_interruptible(&pgdat->kswapd_wait);
}
@@ -1381,6 +1451,8 @@ static unsigned long shrink_all_zones(un
struct zone *zone;
unsigned long nr_to_scan, ret = 0;
+ delay_swap_prefetch();
+
for_each_zone(zone) {
if (!populated_zone(zone))
@@ -1440,7 +1512,7 @@ unsigned long shrink_all_memory(unsigned
.may_swap = 0,
.swap_cluster_max = nr_pages,
.may_writepage = 1,
- .swappiness = vm_swappiness,
+ .mapped = vm_mapped,
};
current->reclaim_state = &reclaim_state;
@@ -1475,7 +1547,7 @@ unsigned long shrink_all_memory(unsigned
/* Force reclaiming mapped pages in the passes #3 and #4 */
if (pass > 2) {
sc.may_swap = 1;
- sc.swappiness = 100;
+ sc.mapped = 0;
}
for (prio = DEF_PRIORITY; prio >= 0; prio--) {
@@ -1539,20 +1611,57 @@ static int __devinit cpu_callback(struct
}
/*
+ * We wake up kswapd every WT_EXPIRY till free ram is above pages_lots
+ */
+static void watermark_wakeup(unsigned long data)
+{
+ pg_data_t *pgdat = (pg_data_t *)data;
+ struct timer_list *wt = &pgdat->watermark_timer;
+ int i;
+
+ if (!waitqueue_active(&pgdat->kswapd_wait) || above_background_load())
+ goto out;
+ for (i = pgdat->nr_zones - 1; i >= 0; i--) {
+ struct zone *z = pgdat->node_zones + i;
+
+ if (!populated_zone(z) || is_highmem(z)) {
+ /* We are better off leaving highmem full */
+ continue;
+ }
+ if (!zone_watermark_ok(z, 0, z->pages_lots, 0, 0)) {
+ wake_up_interruptible(&pgdat->kswapd_wait);
+ goto out;
+ }
+ }
+out:
+ mod_timer(wt, jiffies + WT_EXPIRY);
+ return;
+}
+
+/*
* This kswapd start function will be called by init and node-hot-add.
* On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
*/
int kswapd_run(int nid)
{
pg_data_t *pgdat = NODE_DATA(nid);
+ struct timer_list *wt;
int ret = 0;
if (pgdat->kswapd)
return 0;
+ wt = &pgdat->watermark_timer;
+ init_timer(wt);
+ wt->data = (unsigned long)pgdat;
+ wt->function = watermark_wakeup;
+ wt->expires = jiffies + WT_EXPIRY;
+ add_timer(wt);
+
pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
if (IS_ERR(pgdat->kswapd)) {
/* failure at boot is fatal */
+ del_timer(wt);
BUG_ON(system_state == SYSTEM_BOOTING);
printk("Failed to start kswapd on node %d\n",nid);
ret = -1;
@@ -1623,7 +1732,7 @@ static int __zone_reclaim(struct zone *z
.swap_cluster_max = max_t(unsigned long, nr_pages,
SWAP_CLUSTER_MAX),
.gfp_mask = gfp_mask,
- .swappiness = vm_swappiness,
+ .mapped = vm_mapped,
};
unsigned long slab_reclaimable;
Index: linux-2.6.21-ck1/include/linux/mm_inline.h
===================================================================
--- linux-2.6.21-ck1.orig/include/linux/mm_inline.h 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/include/linux/mm_inline.h 2007-05-04 12:24:20.000000000 +1000
@@ -13,6 +13,13 @@ add_page_to_inactive_list(struct zone *z
}
static inline void
+add_page_to_inactive_list_tail(struct zone *zone, struct page *page)
+{
+ list_add_tail(&page->lru, &zone->inactive_list);
+ __inc_zone_state(zone, NR_INACTIVE);
+}
+
+static inline void
del_page_from_active_list(struct zone *zone, struct page *page)
{
list_del(&page->lru);
Index: linux-2.6.21-ck1/include/linux/swap-prefetch.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.21-ck1/include/linux/swap-prefetch.h 2007-05-04 12:24:20.000000000 +1000
@@ -0,0 +1,55 @@
+#ifndef SWAP_PREFETCH_H_INCLUDED
+#define SWAP_PREFETCH_H_INCLUDED
+
+#ifdef CONFIG_SWAP_PREFETCH
+/* mm/swap_prefetch.c */
+extern int swap_prefetch;
+struct swapped_entry {
+ swp_entry_t swp_entry; /* The actual swap entry */
+ struct list_head swapped_list; /* Linked list of entries */
+#if MAX_NUMNODES > 1
+ int node; /* Node id */
+#endif
+} __attribute__((packed));
+
+static inline void store_swap_entry_node(struct swapped_entry *entry,
+ struct page *page)
+{
+#if MAX_NUMNODES > 1
+ entry->node = page_to_nid(page);
+#endif
+}
+
+static inline int get_swap_entry_node(struct swapped_entry *entry)
+{
+#if MAX_NUMNODES > 1
+ return entry->node;
+#else
+ return 0;
+#endif
+}
+
+extern void add_to_swapped_list(struct page *page);
+extern void remove_from_swapped_list(const unsigned long index);
+extern void delay_swap_prefetch(void);
+extern void prepare_swap_prefetch(void);
+
+#else /* CONFIG_SWAP_PREFETCH */
+static inline void add_to_swapped_list(struct page *__unused)
+{
+}
+
+static inline void prepare_swap_prefetch(void)
+{
+}
+
+static inline void remove_from_swapped_list(const unsigned long __unused)
+{
+}
+
+static inline void delay_swap_prefetch(void)
+{
+}
+#endif /* CONFIG_SWAP_PREFETCH */
+
+#endif /* SWAP_PREFETCH_H_INCLUDED */
Index: linux-2.6.21-ck1/include/linux/sysctl.h
===================================================================
--- linux-2.6.21-ck1.orig/include/linux/sysctl.h 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/include/linux/sysctl.h 2007-05-04 12:24:20.000000000 +1000
@@ -190,7 +190,7 @@ enum
VM_OVERCOMMIT_RATIO=16, /* percent of RAM to allow overcommit in */
VM_PAGEBUF=17, /* struct: Control pagebuf parameters */
VM_HUGETLB_PAGES=18, /* int: Number of available Huge Pages */
- VM_SWAPPINESS=19, /* Tendency to steal mapped memory */
+ VM_MAPPED=19, /* percent mapped min while evicting cache */
VM_LOWMEM_RESERVE_RATIO=20,/* reservation ratio for lower memory zones */
VM_MIN_FREE_KBYTES=21, /* Minimum free kilobytes to maintain */
VM_MAX_MAP_COUNT=22, /* int: Maximum number of mmaps/address-space */
Index: linux-2.6.21-ck1/include/linux/mmzone.h
===================================================================
--- linux-2.6.21-ck1.orig/include/linux/mmzone.h 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/include/linux/mmzone.h 2007-05-04 12:24:21.000000000 +1000
@@ -13,6 +13,7 @@
#include <linux/init.h>
#include <linux/seqlock.h>
#include <linux/nodemask.h>
+#include <linux/timer.h>
#include <asm/atomic.h>
#include <asm/page.h>
@@ -178,7 +179,7 @@ enum zone_type {
struct zone {
/* Fields commonly accessed by the page allocator */
- unsigned long pages_min, pages_low, pages_high;
+ unsigned long pages_min, pages_low, pages_high, pages_lots;
/*
* We don't know if the memory that we're going to allocate will be freeable
* or/and it will be released eventually, so to avoid totally wasting several
@@ -449,6 +450,7 @@ typedef struct pglist_data {
wait_queue_head_t kswapd_wait;
struct task_struct *kswapd;
int kswapd_max_order;
+ struct timer_list watermark_timer;
} pg_data_t;
#define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
@@ -465,7 +467,7 @@ typedef struct pglist_data {
void get_zone_counts(unsigned long *active, unsigned long *inactive,
unsigned long *free);
void build_all_zonelists(void);
-void wakeup_kswapd(struct zone *zone, int order);
+void wakeup_kswapd(struct zone *zone, int order, struct task_struct *p);
int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
int classzone_idx, int alloc_flags);
enum memmap_context {
Index: linux-2.6.21-ck1/mm/page_alloc.c
===================================================================
--- linux-2.6.21-ck1.orig/mm/page_alloc.c 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/mm/page_alloc.c 2007-05-04 12:24:20.000000000 +1000
@@ -1277,7 +1277,7 @@ restart:
goto nopage;
for (z = zonelist->zones; *z; z++)
- wakeup_kswapd(*z, order);
+ wakeup_kswapd(*z, order, p);
/*
* OK, we're below the kswapd watermark and have kicked background
@@ -1341,7 +1341,7 @@ nofail_alloc:
reclaim_state.reclaimed_slab = 0;
p->reclaim_state = &reclaim_state;
- did_some_progress = try_to_free_pages(zonelist->zones, gfp_mask);
+ did_some_progress = try_to_free_pages(zonelist->zones, gfp_mask, p);
p->reclaim_state = NULL;
p->flags &= ~PF_MEMALLOC;
@@ -1597,6 +1597,7 @@ void show_free_areas(void)
" min:%lukB"
" low:%lukB"
" high:%lukB"
+ " lots:%lukB"
" active:%lukB"
" inactive:%lukB"
" present:%lukB"
@@ -1608,6 +1609,7 @@ void show_free_areas(void)
K(zone->pages_min),
K(zone->pages_low),
K(zone->pages_high),
+ K(zone->pages_lots),
K(zone_page_state(zone, NR_ACTIVE)),
K(zone_page_state(zone, NR_INACTIVE)),
K(zone->present_pages),
@@ -3146,6 +3148,7 @@ void setup_per_zone_pages_min(void)
zone->pages_low = zone->pages_min + (tmp >> 2);
zone->pages_high = zone->pages_min + (tmp >> 1);
+ zone->pages_lots = zone->pages_min + tmp;
spin_unlock_irqrestore(&zone->lru_lock, flags);
}
Index: linux-2.6.21-ck1/fs/buffer.c
===================================================================
--- linux-2.6.21-ck1.orig/fs/buffer.c 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/fs/buffer.c 2007-05-04 12:24:20.000000000 +1000
@@ -363,7 +363,7 @@ static void free_more_memory(void)
for_each_online_pgdat(pgdat) {
zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones;
if (*zones)
- try_to_free_pages(zones, GFP_NOFS);
+ try_to_free_pages(zones, GFP_NOFS, NULL);
}
}
Index: linux-2.6.21-ck1/mm/filemap.c
===================================================================
--- linux-2.6.21-ck1.orig/mm/filemap.c 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/mm/filemap.c 2007-05-04 12:24:21.000000000 +1000
@@ -466,6 +466,16 @@ int add_to_page_cache_lru(struct page *p
return ret;
}
+int add_to_page_cache_lru_tail(struct page *page,
+ struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
+{
+ int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
+
+ if (ret == 0)
+ lru_cache_add_tail(page);
+ return ret;
+}
+
#ifdef CONFIG_NUMA
struct page *__page_cache_alloc(gfp_t gfp)
{
@@ -836,6 +846,34 @@ static void shrink_readahead_size_eio(st
ra->ra_pages /= 4;
}
+/*
+ * Sysctl which determines whether we should read from large files to the
+ * tail of the inactive lru list.
+ */
+int vm_tail_largefiles __read_mostly = 1;
+
+static inline int nr_mapped(void)
+{
+ return global_page_state(NR_FILE_MAPPED) +
+ global_page_state(NR_ANON_PAGES);
+}
+
+/*
+ * This examines how large in pages a file size is and returns 1 if it is
+ * more than half the unmapped ram. Avoid doing read_page_state which is
+ * expensive unless we already know it is likely to be large enough.
+ */
+static int large_isize(unsigned long nr_pages)
+{
+ if (nr_pages * 6 > vm_total_pages) {
+ unsigned long unmapped_ram = vm_total_pages - nr_mapped();
+
+ if (nr_pages * 2 > unmapped_ram)
+ return 1;
+ }
+ return 0;
+}
+
/**
* do_generic_mapping_read - generic file read routine
* @mapping: address_space to be read
@@ -1044,8 +1082,19 @@ no_cached_page:
goto out;
}
}
- error = add_to_page_cache_lru(cached_page, mapping,
- index, GFP_KERNEL);
+
+ /*
+ * If we know the file is large we add the pages read to the
+ * end of the lru as we're unlikely to be able to cache the
+ * whole file in ram so make those pages the first to be
+ * dropped if not referenced soon.
+ */
+ if (vm_tail_largefiles && large_isize(end_index))
+ error = add_to_page_cache_lru_tail(cached_page,
+ mapping, index, GFP_KERNEL);
+ else
+ error = add_to_page_cache_lru(cached_page, mapping,
+ index, GFP_KERNEL);
if (error) {
if (error == -EEXIST)
goto find_page;
Index: linux-2.6.21-ck1/Documentation/filesystems/proc.txt
===================================================================
--- linux-2.6.21-ck1.orig/Documentation/filesystems/proc.txt 2007-05-04 12:24:01.000000000 +1000
+++ linux-2.6.21-ck1/Documentation/filesystems/proc.txt 2007-05-04 12:24:21.000000000 +1000
@@ -1325,6 +1325,14 @@ To free pagecache, dentries and inodes:
As this is a non-destructive operation and dirty objects are not freeable, the
user should run `sync' first.
+tail_largefiles
+---------------
+
+When enabled reads from large files to the tail end of the inactive lru list.
+This means that any cache from reading large files is dropped very quickly,
+preventing loss of mapped ram and useful pagecache when large files are read.
+This does, however, make caching less effective when working with large files.
+
2.5 /proc/sys/dev - Device specific parameters
----------------------------------------------
Index: linux-2.6.21-ck1/arch/i386/Kconfig
===================================================================
--- linux-2.6.21-ck1.orig/arch/i386/Kconfig 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/arch/i386/Kconfig 2007-05-04 12:24:21.000000000 +1000
@@ -546,7 +546,7 @@ endchoice
choice
depends on EXPERIMENTAL
- prompt "Memory split" if EMBEDDED
+ prompt "Memory split"
default VMSPLIT_3G
help
Select the desired split between kernel and user memory.
@@ -565,14 +565,14 @@ choice
option alone!
config VMSPLIT_3G
- bool "3G/1G user/kernel split"
+ bool "Default 896MB lowmem (3G/1G user/kernel split)"
config VMSPLIT_3G_OPT
depends on !HIGHMEM
- bool "3G/1G user/kernel split (for full 1G low memory)"
+ bool "1GB lowmem (3G/1G user/kernel split)"
config VMSPLIT_2G
- bool "2G/2G user/kernel split"
+ bool "2GB lowmem (2G/2G user/kernel split)"
config VMSPLIT_1G
- bool "1G/3G user/kernel split"
+ bool "3GB lowmem (1G/3G user/kernel split)"
endchoice
config PAGE_OFFSET
Index: linux-2.6.21-ck1/kernel/Kconfig.hz
===================================================================
--- linux-2.6.21-ck1.orig/kernel/Kconfig.hz 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/kernel/Kconfig.hz 2007-05-04 12:24:21.000000000 +1000
@@ -4,7 +4,7 @@
choice
prompt "Timer frequency"
- default HZ_250
+ default HZ_1000
help
Allows the configuration of the timer frequency. It is customary
to have the timer interrupt run at 1000 Hz but 100 Hz may be more
@@ -13,8 +13,7 @@ choice
contention and cacheline bounces as a result of timer interrupts.
Note that the timer interrupt occurs on each processor in an SMP
environment leading to NR_CPUS * HZ number of timer interrupts
- per second.
-
+ per second.Laptops may also show improved battery life.
config HZ_100
bool "100 HZ"
@@ -23,13 +22,14 @@ choice
with lots of processors that may show reduced performance if
too many timer interrupts are occurring.
- config HZ_250
+ config HZ_250_NODEFAULT
bool "250 HZ"
help
- 250 Hz is a good compromise choice allowing server performance
- while also showing good interactive responsiveness even
- on SMP and NUMA systems. If you are going to be using NTSC video
- or multimedia, selected 300Hz instead.
+ 250 HZ is a lousy compromise choice allowing server interactivity
+ while also showing desktop throughput and no extra power saving on
+ laptops. Good for when you can't make up your mind.
+
+ Recommend 100 or 1000 instead.
config HZ_300
bool "300 HZ"
@@ -45,12 +45,76 @@ choice
1000 Hz is the preferred choice for desktop systems and other
systems requiring fast interactive responses to events.
+ config HZ_1500
+ bool "1500 HZ"
+ help
+ 1500 Hz is an insane value to use to run broken software that is Hz
+ limited.
+
+ Being over 1000, driver breakage is likely.
+
+ config HZ_2000
+ bool "2000 HZ"
+ help
+ 2000 Hz is an insane value to use to run broken software that is Hz
+ limited.
+
+ Being over 1000, driver breakage is likely.
+
+ config HZ_3000
+ bool "3000 HZ"
+ help
+ 3000 Hz is an insane value to use to run broken software that is Hz
+ limited.
+
+ Being over 1000, driver breakage is likely.
+
+ config HZ_4000
+ bool "4000 HZ"
+ help
+ 4000 Hz is an insane value to use to run broken software that is Hz
+ limited.
+
+ Being over 1000, driver breakage is likely.
+
+ config HZ_5000
+ bool "5000 HZ"
+ help
+ 5000 Hz is an obscene value to use to run broken software that is Hz
+ limited.
+
+ Being over 1000, driver breakage is likely.
+
+ config HZ_7500
+ bool "7500 HZ"
+ help
+ 7500 Hz is an obscene value to use to run broken software that is Hz
+ limited.
+
+ Being over 1000, driver breakage is likely.
+
+ config HZ_10000
+ bool "10000 HZ"
+ help
+ 10000 Hz is an obscene value to use to run broken software that is Hz
+ limited.
+
+ Being over 1000, driver breakage is likely.
+
+
endchoice
config HZ
int
default 100 if HZ_100
- default 250 if HZ_250
+ default 250 if HZ_250_NODEFAULT
default 300 if HZ_300
default 1000 if HZ_1000
+ default 1500 if HZ_1500
+ default 2000 if HZ_2000
+ default 3000 if HZ_3000
+ default 4000 if HZ_4000
+ default 5000 if HZ_5000
+ default 7500 if HZ_7500
+ default 10000 if HZ_10000
Index: linux-2.6.21-ck1/arch/i386/defconfig
===================================================================
--- linux-2.6.21-ck1.orig/arch/i386/defconfig 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/arch/i386/defconfig 2007-05-04 12:24:21.000000000 +1000
@@ -214,10 +214,10 @@ CONFIG_MTRR=y
# CONFIG_IRQBALANCE is not set
CONFIG_SECCOMP=y
# CONFIG_HZ_100 is not set
-CONFIG_HZ_250=y
+# CONFIG_HZ_250 is not set
# CONFIG_HZ_300 is not set
-# CONFIG_HZ_1000 is not set
-CONFIG_HZ=250
+CONFIG_HZ_1000=y
+CONFIG_HZ=1000
# CONFIG_KEXEC is not set
# CONFIG_CRASH_DUMP is not set
CONFIG_PHYSICAL_START=0x100000
Index: linux-2.6.21-ck1/arch/x86_64/defconfig
===================================================================
--- linux-2.6.21-ck1.orig/arch/x86_64/defconfig 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/arch/x86_64/defconfig 2007-05-04 12:24:21.000000000 +1000
@@ -178,10 +178,10 @@ CONFIG_PHYSICAL_START=0x200000
CONFIG_SECCOMP=y
# CONFIG_CC_STACKPROTECTOR is not set
# CONFIG_HZ_100 is not set
-CONFIG_HZ_250=y
+# CONFIG_HZ_250 is not set
# CONFIG_HZ_300 is not set
-# CONFIG_HZ_1000 is not set
-CONFIG_HZ=250
+CONFIG_HZ_1000=y
+CONFIG_HZ=1000
# CONFIG_REORDER is not set
CONFIG_K8_NB=y
CONFIG_GENERIC_HARDIRQS=y
Index: linux-2.6.21-ck1/include/linux/jiffies.h
===================================================================
--- linux-2.6.21-ck1.orig/include/linux/jiffies.h 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/include/linux/jiffies.h 2007-05-04 12:24:21.000000000 +1000
@@ -29,6 +29,12 @@
# define SHIFT_HZ 9
#elif HZ >= 768 && HZ < 1536
# define SHIFT_HZ 10
+#elif HZ >= 1536 && HZ < 3072
+# define SHIFT_HZ 11
+#elif HZ >= 3072 && HZ < 6144
+# define SHIFT_HZ 12
+#elif HZ >= 6144 && HZ < 12288
+# define SHIFT_HZ 13
#else
# error You lose.
#endif
Index: linux-2.6.21-ck1/include/net/inet_timewait_sock.h
===================================================================
--- linux-2.6.21-ck1.orig/include/net/inet_timewait_sock.h 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/include/net/inet_timewait_sock.h 2007-05-04 12:24:21.000000000 +1000
@@ -38,8 +38,8 @@ struct inet_hashinfo;
* If time > 4sec, it is "slow" path, no recycling is required,
* so that we select tick to get range about 4 seconds.
*/
-#if HZ <= 16 || HZ > 4096
-# error Unsupported: HZ <= 16 or HZ > 4096
+#if HZ <= 16 || HZ > 16384
+# error Unsupported: HZ <= 16 or HZ > 16384
#elif HZ <= 32
# define INET_TWDR_RECYCLE_TICK (5 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
#elif HZ <= 64
@@ -54,8 +54,12 @@ struct inet_hashinfo;
# define INET_TWDR_RECYCLE_TICK (10 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
#elif HZ <= 2048
# define INET_TWDR_RECYCLE_TICK (11 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
-#else
+#elif HZ <= 4096
# define INET_TWDR_RECYCLE_TICK (12 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
+#elif HZ <= 8192
+# define INET_TWDR_RECYCLE_TICK (13 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
+#else
+# define INET_TWDR_RECYCLE_TICK (14 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
#endif
/* TIME_WAIT reaping mechanism. */
Index: linux-2.6.21-ck1/include/net/pkt_sched.h
===================================================================
--- linux-2.6.21-ck1.orig/include/net/pkt_sched.h 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/include/net/pkt_sched.h 2007-05-04 12:24:21.000000000 +1000
@@ -78,8 +78,14 @@ typedef long psched_tdiff_t;
#define PSCHED_JSCALE 12
#elif HZ >= 384 && HZ < 768
#define PSCHED_JSCALE 11
-#elif HZ >= 768
+#elif HZ >= 768 && HZ < 1536
#define PSCHED_JSCALE 10
+#elif HZ >= 1536 && HZ < 3072
+#define PSCHED_JSCALE 9
+#elif HZ >= 3072 && HZ < 6144
+#define PSCHED_JSCALE 8
+#else
+#define PSCHED_JSCALE 7
#endif
#define PSCHED_GET_TIME(stamp) ((stamp) = (get_jiffies_64()<<PSCHED_JSCALE))
Index: linux-2.6.21-ck1/init/calibrate.c
===================================================================
--- linux-2.6.21-ck1.orig/init/calibrate.c 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/init/calibrate.c 2007-05-04 12:24:21.000000000 +1000
@@ -122,12 +122,12 @@ void __devinit calibrate_delay(void)
printk("Calibrating delay loop (skipped)... "
"%lu.%02lu BogoMIPS preset\n",
loops_per_jiffy/(500000/HZ),
- (loops_per_jiffy/(5000/HZ)) % 100);
+ (loops_per_jiffy * 10/(50000/HZ)) % 100);
} else if ((loops_per_jiffy = calibrate_delay_direct()) != 0) {
printk("Calibrating delay using timer specific routine.. ");
printk("%lu.%02lu BogoMIPS (lpj=%lu)\n",
loops_per_jiffy/(500000/HZ),
- (loops_per_jiffy/(5000/HZ)) % 100,
+ (loops_per_jiffy * 10/(50000/HZ)) % 100,
loops_per_jiffy);
} else {
loops_per_jiffy = (1<<12);
@@ -166,7 +166,7 @@ void __devinit calibrate_delay(void)
/* Round the value and print it */
printk("%lu.%02lu BogoMIPS (lpj=%lu)\n",
loops_per_jiffy/(500000/HZ),
- (loops_per_jiffy/(5000/HZ)) % 100,
+ (loops_per_jiffy * 10/(50000/HZ)) % 100,
loops_per_jiffy);
}
Index: linux-2.6.21-ck1/arch/i386/kernel/cpu/proc.c
===================================================================
--- linux-2.6.21-ck1.orig/arch/i386/kernel/cpu/proc.c 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/arch/i386/kernel/cpu/proc.c 2007-05-04 12:24:21.000000000 +1000
@@ -158,7 +158,7 @@ static int show_cpuinfo(struct seq_file
seq_printf(m, "\nbogomips\t: %lu.%02lu\n",
c->loops_per_jiffy/(500000/HZ),
- (c->loops_per_jiffy/(5000/HZ)) % 100);
+ (c->loops_per_jiffy * 10/(50000/HZ)) % 100);
seq_printf(m, "clflush size\t: %u\n\n", c->x86_clflush_size);
return 0;
Index: linux-2.6.21-ck1/arch/i386/kernel/smpboot.c
===================================================================
--- linux-2.6.21-ck1.orig/arch/i386/kernel/smpboot.c 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/arch/i386/kernel/smpboot.c 2007-05-04 12:24:21.000000000 +1000
@@ -1134,7 +1134,7 @@ static void __init smp_boot_cpus(unsigne
"Total of %d processors activated (%lu.%02lu BogoMIPS).\n",
cpucount+1,
bogosum/(500000/HZ),
- (bogosum/(5000/HZ))%100);
+ (bogosum * 10/(50000/HZ))%100);
Dprintk("Before bogocount - setting activated=1.\n");
Index: linux-2.6.21-ck1/include/linux/nfsd/stats.h
===================================================================
--- linux-2.6.21-ck1.orig/include/linux/nfsd/stats.h 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/include/linux/nfsd/stats.h 2007-05-04 12:24:21.000000000 +1000
@@ -35,8 +35,8 @@ struct nfsd_stats {
};
-/* thread usage wraps very million seconds (approx one fortnight) */
-#define NFSD_USAGE_WRAP (HZ*1000000)
+/* thread usage wraps every one hundred thousand seconds (approx one day) */
+#define NFSD_USAGE_WRAP (HZ*100000)
#ifdef __KERNEL__
Index: linux-2.6.21-ck1/arch/x86_64/kernel/setup.c
===================================================================
--- linux-2.6.21-ck1.orig/arch/x86_64/kernel/setup.c 2007-05-04 12:24:00.000000000 +1000
+++ linux-2.6.21-ck1/arch/x86_64/kernel/setup.c 2007-05-04 12:24:22.000000000 +1000
@@ -1053,7 +1053,7 @@ static int show_cpuinfo(struct seq_file
seq_printf(m, "\nbogomips\t: %lu.%02lu\n",
c->loops_per_jiffy/(500000/HZ),
- (c->loops_per_jiffy/(5000/HZ)) % 100);
+ (c->loops_per_jiffy * 10/(50000/HZ)) % 100);
if (c->x86_tlbsize > 0)
seq_printf(m, "TLB size\t: %d 4K pages\n", c->x86_tlbsize);
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