Re: 2.6 vs 2.4, ssh terminal slowdown
From: MIke Galbraith
Date: Sun Feb 12 2006 - 16:29:21 EST
On Sun, 2006-02-12 at 14:03 -0500, Lee Revell wrote:
> On Sun, 2006-02-12 at 14:47 +0100, MIke Galbraith wrote:
> > If you think it's the scheduler, how about try the patch below. It's
> > against 2.6.16-rc2-mm1, and should tell you if it is the interactivity
> > logic in the scheduler or not. I don't see other candidates in there,
> > not that that means there aren't any of course.
>
> I'll try, but it's a serious pain for me to build an -mm kernel. A
> patch against 2.6.16-rc1 would be much easier.
Ok, here she comes. It's a bit too reluctant to release a task so it
can reach interactive status at the moment, but for this test, that's a
feature. In fact, for this test, it's probably best to jump straight to
setting both g1 and g2 to zero.
-Mike
--- linux-2.6.16-rc1/include/linux/sched.h.org 2006-02-12 21:28:28.000000000 +0100
+++ linux-2.6.16-rc1/include/linux/sched.h 2006-02-12 21:54:40.000000000 +0100
@@ -688,6 +688,13 @@
struct audit_context; /* See audit.c */
struct mempolicy;
+enum sleep_type {
+ SLEEP_NORMAL,
+ SLEEP_NONINTERACTIVE,
+ SLEEP_INTERACTIVE,
+ SLEEP_INTERRUPTED,
+};
+
struct task_struct {
volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */
struct thread_info *thread_info;
@@ -709,14 +716,14 @@
unsigned short ioprio;
- unsigned long sleep_avg;
+ unsigned long sleep_avg, last_slice, throttle_stamp;
unsigned long long timestamp, last_ran;
unsigned long long sched_time; /* sched_clock time spent running */
- int activated;
+ enum sleep_type sleep_type;
unsigned long policy;
cpumask_t cpus_allowed;
- unsigned int time_slice, first_time_slice;
+ unsigned int time_slice, slice_info;
#ifdef CONFIG_SCHEDSTATS
struct sched_info sched_info;
--- linux-2.6.16-rc1/include/linux/sysctl.h.org 2006-02-12 21:28:44.000000000 +0100
+++ linux-2.6.16-rc1/include/linux/sysctl.h 2006-02-12 21:34:46.000000000 +0100
@@ -146,6 +146,8 @@
KERN_RANDOMIZE=68, /* int: randomize virtual address space */
KERN_SETUID_DUMPABLE=69, /* int: behaviour of dumps for setuid core */
KERN_SPIN_RETRY=70, /* int: number of spinlock retries */
+ KERN_SCHED_THROTTLE1=71, /* int: throttling grace period 1 in secs */
+ KERN_SCHED_THROTTLE2=72, /* int: throttling grace period 2 in secs */
};
--- linux-2.6.16-rc1/kernel/sched.c.org 2006-02-12 21:29:13.000000000 +0100
+++ linux-2.6.16-rc1/kernel/sched.c 2006-02-12 21:58:14.000000000 +0100
@@ -149,9 +149,195 @@
#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))
+/*
+ * Interactivity boost can lead to serious starvation problems if the
+ * task being boosted turns out to be a cpu hog. To combat this, we
+ * compute a running slice_avg, which is the sane upper limit for the
+ * task's sleep_avg. If an 'interactive' task begins burning cpu, it's
+ * slice_avg will decay, making it visible as a problem so corrective
+ * measures can be applied.
+ *
+ * /proc/sys/kernel tunables.
+ *
+ * sched_g1: Grace period in seconds that a task is allowed to run unchecked.
+ * sched_g2: seconds thereafter, to force a priority adjustment.
+ */
+
+int sched_g1 = 20;
+int sched_g2 = 10;
+
+/*
+ * Offset from the time we noticed a potential problem until we disable the
+ * interactive bonus multiplier, and adjust sleep_avg consumption rate.
+ */
+#define G1 (sched_g1 * HZ)
+
+/*
+ * Offset thereafter that we disable the interactive bonus divisor, and adjust
+ * a runaway task's priority.
+ */
+#define G2 (sched_g2 * HZ + G1)
+
+/*
+ * Grace period has expired.
+ */
+#define grace_expired(p, grace) ((p)->throttle_stamp && \
+ time_after_eq(jiffies, (p)->throttle_stamp + (grace)))
+
+#define NEXT_PRIO (NS_MAX_SLEEP_AVG / MAX_BONUS)
+
+/*
+ * Warning: do not reduce threshold below NS_MAX_SLEEP_AVG / MAX_BONUS
+ * else you may break the case where one of a pair of communicating tasks
+ * only sleeps a miniscule amount of time, but must to be able to preempt
+ * it's partner in order to get any cpu time to speak of. If you push that
+ * task to the same level or below it's partner, it will not be able to
+ * preempt and will starve. This scenario was fixed for bonus calculation
+ * by converting sleep_avg to ns.
+ */
+#define THROTTLE_THRESHOLD (NEXT_PRIO)
+
+#define NS_MAX_SLEEP_AVG_PCNT (NS_MAX_SLEEP_AVG / 100)
+
+/*
+ * Masks for p->slice_info, formerly p->first_time_slice.
+ * SLICE_FTS: 0x80000000 Task is in it's first ever timeslice.
+ * SLICE_NEW: 0x40000000 Slice refreshed.
+ * SLICE_SPA: 0x3FFF8000 Spare bits.
+ * SLICE_LTS: 0x00007F80 Last time slice
+ * SLICE_AVG: 0x0000007F Task slice_avg stored as percentage.
+ */
+#define SLICE_AVG_BITS 7
+#define SLICE_LTS_BITS 10
+#define SLICE_SPA_BITS 13
+#define SLICE_NEW_BITS 1
+#define SLICE_FTS_BITS 1
+
+#define SLICE_AVG_SHIFT 0
+#define SLICE_LTS_SHIFT (SLICE_AVG_SHIFT + SLICE_AVG_BITS)
+#define SLICE_SPA_SHIFT (SLICE_LTS_SHIFT + SLICE_LTS_BITS)
+#define SLICE_NEW_SHIFT (SLICE_SPA_SHIFT + SLICE_SPA_BITS)
+#define SLICE_FTS_SHIFT (SLICE_NEW_SHIFT + SLICE_NEW_BITS)
+
+#define INFO_MASK(x) ((1U << (x))-1)
+#define SLICE_AVG_MASK (INFO_MASK(SLICE_AVG_BITS) << SLICE_AVG_SHIFT)
+#define SLICE_LTS_MASK (INFO_MASK(SLICE_LTS_BITS) << SLICE_LTS_SHIFT)
+#define SLICE_SPA_MASK (INFO_MASK(SLICE_SPA_BITS) << SLICE_SPA_SHIFT)
+#define SLICE_NEW_MASK (INFO_MASK(SLICE_NEW_BITS) << SLICE_NEW_SHIFT)
+#define SLICE_FTS_MASK (INFO_MASK(SLICE_FTS_BITS) << SLICE_FTS_SHIFT)
+
+#define first_time_slice(p) ((p)->slice_info & SLICE_FTS_MASK)
+#define set_first_time_slice(p) ((p)->slice_info |= SLICE_FTS_MASK)
+#define clr_first_time_slice(p) ((p)->slice_info &= ~SLICE_FTS_MASK)
+
+#define slice_is_new(p) ((p)->slice_info & SLICE_NEW_MASK)
+#define set_slice_is_new(p) ((p)->slice_info |= SLICE_NEW_MASK)
+#define clr_slice_is_new(p) ((p)->slice_info &= ~SLICE_NEW_MASK)
+
+#define last_slice(p) \
+ ((((p)->slice_info & SLICE_LTS_MASK) >> SLICE_LTS_SHIFT) ? : \
+ DEF_TIMESLICE)
+#define set_last_slice(p, n) ((p)->slice_info = (((p)->slice_info & \
+ ~SLICE_LTS_MASK) | (((n) << SLICE_LTS_SHIFT) & SLICE_LTS_MASK)))
+
+#define slice_avg(p) \
+ ((((p)->slice_info & SLICE_AVG_MASK) >> SLICE_AVG_SHIFT) * \
+ NS_MAX_SLEEP_AVG_PCNT)
+#define set_slice_avg(p, n) ((p)->slice_info = (((p)->slice_info & \
+ ~SLICE_AVG_MASK) | ((((n) / NS_MAX_SLEEP_AVG_PCNT) \
+ << SLICE_AVG_SHIFT) & SLICE_AVG_MASK)))
+#define slice_avg_raw(p) \
+ (((p)->slice_info & SLICE_AVG_MASK) >> SLICE_AVG_SHIFT)
+#define set_slice_avg_raw(p, n) ((p)->slice_info = (((p)->slice_info & \
+ ~SLICE_AVG_MASK) | (((n) << SLICE_AVG_SHIFT) & SLICE_AVG_MASK)))
+
+#define cpu_avg(p) \
+ (100 - slice_avg_raw(p))
+
+#define slice_time_avg(p) \
+ (100 * last_slice(p) / max((unsigned)cpu_avg(p), 1U))
+
+#define time_this_slice(p) \
+ (jiffies - (p)->last_slice)
+
+#define cpu_this_slice(p) \
+ (100 * last_slice(p) / max((unsigned)time_this_slice(p), \
+ (unsigned)last_slice(p)))
+
+#define this_slice_avg(p) \
+ ((100 - cpu_this_slice(p)) * NS_MAX_SLEEP_AVG_PCNT)
+
+/*
+ * In order to prevent tasks from thrashing between domesticated livestock
+ * and irate rhino, once a throttle is hung on a task, the only way to get
+ * rid of it is to change behavior. We push the throttle stamp forward in
+ * time as things improve until the stamp is in the future. Only then may
+ * we safely pull our 'tranquilizer dart'.
+ */
+#define conditional_tag(p) ((!(p)->throttle_stamp && \
+ (p)->sleep_avg > slice_avg(p) + THROTTLE_THRESHOLD) ? \
+({ \
+ ((p)->throttle_stamp = jiffies) ? : 1; \
+}) : 0)
+
+/*
+ * Those who use the least cpu receive the most encouragement.
+ */
+#define SLICE_AVG_MULTIPLIER(p) \
+ (1 + NS_TO_JIFFIES(this_slice_avg(p)) * MAX_BONUS / MAX_SLEEP_AVG)
+
+#define conditional_release(p) (((p)->throttle_stamp && \
+ (p)->sched_time >= (G2 ? JIFFIES_TO_NS(HZ) : ~0ULL) && \
+ ((20 + cpu_this_slice(p) < cpu_avg(p) && (p)->sleep_avg < \
+ slice_avg(p) + THROTTLE_THRESHOLD) || cpu_avg(p) <= 5)) ? \
+({ \
+ int __ret = 0; \
+ int delay = slice_time_avg(p) - last_slice(p); \
+ if (delay > 0) { \
+ delay *= SLICE_AVG_MULTIPLIER(p); \
+ (p)->throttle_stamp += delay; \
+ } \
+ if (time_before(jiffies, (p)->throttle_stamp)) { \
+ (p)->throttle_stamp = 0; \
+ __ret++; \
+ if (!((p)->state & TASK_NONINTERACTIVE)) \
+ (p)->sleep_type = SLEEP_NORMAL; \
+ } \
+ __ret; \
+}) : 0)
+
+/*
+ * CURRENT_BONUS(p) adjusted to match slice_avg after grace expiration.
+ */
+#define ADJUSTED_BONUS(p, grace) \
+({ \
+ unsigned long sleep_avg = (p)->sleep_avg; \
+ if (grace_expired(p, (grace))) \
+ sleep_avg = min((unsigned long)(p)->sleep_avg, \
+ (unsigned long)slice_avg(p)); \
+ NS_TO_JIFFIES(sleep_avg) * MAX_BONUS / MAX_SLEEP_AVG; \
+})
+
+#define BONUS_MULTIPLIER(p) \
+ (grace_expired(p, G1) ? : SLICE_AVG_MULTIPLIER(p))
+
+#define BONUS_DIVISOR(p) \
+ (grace_expired(p, G2) ? : (1 + ADJUSTED_BONUS(p, G1)))
+
+#define INTERACTIVE_SLEEP_AVG(p) \
+ (min(JIFFIES_TO_NS(MAX_SLEEP_AVG * (MAX_BONUS / 2 + DELTA(p)) / MAX_BONUS), \
+ NS_MAX_SLEEP_AVG))
+
+/*
+ * The quantity of sleep quaranteed to elevate a task to interactive status,
+ * or if already there, to elevate it to the next priority or beyond.
+ */
+#define INTERACTIVE_SLEEP_NS(p, ns) \
+ (BONUS_MULTIPLIER(p) * (ns) >= INTERACTIVE_SLEEP_AVG(p) || \
+ ((p)->sleep_avg < INTERACTIVE_SLEEP_AVG(p) && BONUS_MULTIPLIER(p) * \
+ (ns) + (p)->sleep_avg >= INTERACTIVE_SLEEP_AVG(p)) || \
+ ((p)->sleep_avg >= INTERACTIVE_SLEEP_AVG(p) && BONUS_MULTIPLIER(p) * \
+ (ns) + ((p)->sleep_avg % NEXT_PRIO) >= NEXT_PRIO))
#define TASK_PREEMPTS_CURR(p, rq) \
((p)->prio < (rq)->curr->prio)
@@ -659,7 +845,7 @@
if (rt_task(p))
return p->prio;
- bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
+ bonus = ADJUSTED_BONUS(p, G2) - MAX_BONUS / 2;
prio = p->static_prio - bonus;
if (prio < MAX_RT_PRIO)
@@ -759,36 +945,50 @@
if (likely(sleep_time > 0)) {
/*
- * User tasks that sleep a long time are categorised as
- * idle and will get just interactive status to stay active &
- * prevent them suddenly becoming cpu hogs and starving
- * other processes.
+ * Tasks that sleep a long time are categorised as idle.
+ * They will only have their sleep_avg increased to a
+ * level that makes them just interactive priority to stay
+ * active yet prevent them suddenly becoming cpu hogs and
+ * starving other processes. All tasks must stop at each
+ * TASK_INTERACTIVE boundry before moving on so that no
+ * single sleep slams it straight into NS_MAX_SLEEP_AVG.
*/
- if (p->mm && p->activated != -1 &&
- sleep_time > INTERACTIVE_SLEEP(p)) {
- p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG -
- DEF_TIMESLICE);
+ if (INTERACTIVE_SLEEP_NS(p, sleep_time)) {
+ int ticks = last_slice(p) / BONUS_DIVISOR(p);
+ unsigned long ceiling = INTERACTIVE_SLEEP_AVG(p);
+
+ ticks = JIFFIES_TO_NS(ticks);
+
+ if (grace_expired(p, G2) && slice_avg(p) < ceiling)
+ ceiling = slice_avg(p);
+ /* Promote previously interactive task. */
+ else if (p->sleep_avg >= INTERACTIVE_SLEEP_AVG(p) &&
+ !grace_expired(p, G2)) {
+
+ ceiling = p->sleep_avg / NEXT_PRIO;
+ if (ceiling < MAX_BONUS)
+ ceiling++;
+ ceiling *= NEXT_PRIO;
+ }
+
+ ceiling += ticks;
+
+ if (ceiling > NS_MAX_SLEEP_AVG)
+ ceiling = NS_MAX_SLEEP_AVG;
+
+ if (p->sleep_avg < ceiling)
+ p->sleep_avg = ceiling;
} else {
- /*
- * The lower the sleep avg a task has the more
- * rapidly it will rise with sleep time.
- */
- sleep_time *= (MAX_BONUS - CURRENT_BONUS(p)) ? : 1;
/*
- * Tasks waking from uninterruptible sleep are
- * limited in their sleep_avg rise as they
- * are likely to be waiting on I/O
+ * The lower the sleep avg a task has the more
+ * rapidly it will rise with sleep time. This enables
+ * tasks to rapidly recover to a low latency priority.
+ * If a task was sleeping with the noninteractive
+ * label do not apply this non-linear boost
*/
- if (p->activated == -1 && p->mm) {
- if (p->sleep_avg >= INTERACTIVE_SLEEP(p))
- sleep_time = 0;
- else if (p->sleep_avg + sleep_time >=
- INTERACTIVE_SLEEP(p)) {
- p->sleep_avg = INTERACTIVE_SLEEP(p);
- sleep_time = 0;
- }
- }
+ if (p->sleep_type != SLEEP_NONINTERACTIVE)
+ sleep_time *= BONUS_MULTIPLIER(p);
/*
* This code gives a bonus to interactive tasks.
@@ -835,7 +1035,7 @@
* This checks to make sure it's not an uninterruptible task
* that is now waking up.
*/
- if (!p->activated) {
+ if (p->sleep_type != SLEEP_NONINTERACTIVE) {
/*
* Tasks which were woken up by interrupts (ie. hw events)
* are most likely of interactive nature. So we give them
@@ -844,13 +1044,13 @@
* on a CPU, first time around:
*/
if (in_interrupt())
- p->activated = 2;
+ 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->activated = 1;
+ p->sleep_type = SLEEP_INTERACTIVE;
}
}
p->timestamp = now;
@@ -1371,25 +1571,28 @@
out_activate:
#endif /* CONFIG_SMP */
- if (old_state == TASK_UNINTERRUPTIBLE) {
- rq->nr_uninterruptible--;
+
+ conditional_release(p);
+
+ if (old_state & TASK_UNINTERRUPTIBLE) {
/*
- * Tasks on involuntary sleep don't earn
- * sleep_avg beyond just interactive state.
+ * Tasks waking from uninterruptible sleep are likely
+ * to be sleeping involuntarily on I/O and are otherwise
+ * cpu bound so label them as noninteractive.
*/
- p->activated = -1;
- }
+ p->sleep_type = SLEEP_NONINTERACTIVE;
+ } else
/*
* Tasks that have marked their sleep as noninteractive get
- * woken up without updating their sleep average. (i.e. their
- * sleep is handled in a priority-neutral manner, no priority
- * boost and no penalty.)
+ * woken up with their sleep average not weighted in an
+ * interactive way.
*/
- if (old_state & TASK_NONINTERACTIVE)
- __activate_task(p, rq);
- else
- activate_task(p, rq, cpu == this_cpu);
+ 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)
@@ -1471,9 +1674,27 @@
* The remainder of the first timeslice might be recovered by
* the parent if the child exits early enough.
*/
- p->first_time_slice = 1;
+ set_first_time_slice(p);
current->time_slice >>= 1;
p->timestamp = sched_clock();
+
+ /*
+ * Set up slice_info for the child.
+ *
+ * Note: The child inherits the parent's throttle,
+ * and must shake it loose. It does not inherit
+ * the parent's slice_avg.
+ */
+ set_slice_avg(p, NS_MAX_SLEEP_AVG);
+ set_last_slice(p, p->time_slice);
+ set_slice_is_new(p);
+ p->last_slice = jiffies;
+ /*
+ * Limit the difficulty to what the parent faced.
+ */
+ if (p->throttle_stamp && grace_expired(p, G2))
+ p->throttle_stamp = jiffies - G2;
+
if (unlikely(!current->time_slice)) {
/*
* This case is rare, it happens when the parent has only
@@ -1587,7 +1808,7 @@
* 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)) {
+ if (first_time_slice(p) && 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);
@@ -2655,6 +2876,51 @@
}
/*
+ * Calculate a task's average cpu usage rate in terms of sleep_avg, and
+ * check whether the task may soon need throttling. Must be called after
+ * refreshing the task's time slice.
+ * @p: task for which slice_avg should be computed.
+ */
+static void recalc_task_slice_avg(task_t *p)
+{
+ unsigned int slice_avg = slice_avg_raw(p);
+ unsigned int time_slice = last_slice(p);
+ int w = MAX_BONUS, idle;
+
+ if (unlikely(!time_slice))
+ set_last_slice(p, p->time_slice);
+
+ idle = 100 - cpu_this_slice(p);
+
+ /*
+ * If the task is lowering it's cpu usage, speed up the
+ * effect on slice_avg so we don't over-throttle.
+ */
+ if (idle > slice_avg) {
+ w -= idle / w;
+ if (!w)
+ w = 1;
+ }
+
+ slice_avg = (w * (slice_avg ? : 1) + idle) / (w + 1);
+
+ /* Check to see if we should start/stop throttling. */
+ if(!rt_task(p) && !conditional_release(p))
+ conditional_tag(p);
+
+ /* Update slice_avg. */
+ set_slice_avg_raw(p, slice_avg);
+
+ /* Update cached slice length. */
+ if (time_slice != p->time_slice)
+ set_last_slice(p, p->time_slice);
+
+ /* And finally, stamp and tag the new slice. */
+ set_slice_is_new(p);
+ p->last_slice = jiffies;
+}
+
+/*
* This function gets called by the timer code, with HZ frequency.
* We call it with interrupts disabled.
*
@@ -2699,20 +2965,24 @@
*/
if ((p->policy == SCHED_RR) && !--p->time_slice) {
p->time_slice = task_timeslice(p);
- p->first_time_slice = 0;
+ recalc_task_slice_avg(p);
+ clr_first_time_slice(p);
set_tsk_need_resched(p);
/* put it at the end of the queue: */
requeue_task(p, rq->active);
}
+ if (unlikely(p->throttle_stamp))
+ p->throttle_stamp = 0;
goto out_unlock;
}
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;
+ recalc_task_slice_avg(p);
+ p->prio = effective_prio(p);
+ clr_first_time_slice(p);
if (!rq->expired_timestamp)
rq->expired_timestamp = jiffies;
@@ -2959,6 +3229,12 @@
#endif
+static inline int interactive_sleep(enum sleep_type sleep_type)
+{
+ return (sleep_type == SLEEP_INTERACTIVE ||
+ sleep_type == SLEEP_INTERRUPTED);
+}
+
/*
* schedule() is the main scheduler function.
*/
@@ -3017,7 +3293,7 @@
* Tasks charged proportionately less run_time at high sleep_avg to
* delay them losing their interactive status
*/
- run_time /= (CURRENT_BONUS(prev) ? : 1);
+ run_time /= BONUS_DIVISOR(prev);
spin_lock_irq(&rq->lock);
@@ -3031,7 +3307,7 @@
unlikely(signal_pending(prev))))
prev->state = TASK_RUNNING;
else {
- if (prev->state == TASK_UNINTERRUPTIBLE)
+ if (prev->state & TASK_UNINTERRUPTIBLE)
rq->nr_uninterruptible++;
deactivate_task(prev, rq);
}
@@ -3080,16 +3356,17 @@
rq->best_expired_prio = MAX_PRIO;
}
+repeat_selection:
idx = sched_find_first_bit(array->bitmap);
queue = array->queue + idx;
next = list_entry(queue->next, task_t, run_list);
- if (!rt_task(next) && next->activated > 0) {
+ 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->activated == 1)
+ if (next->sleep_type == SLEEP_INTERACTIVE)
delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;
array = next->array;
@@ -3099,10 +3376,16 @@
dequeue_task(next, array);
next->prio = new_prio;
enqueue_task(next, array);
- } else
- requeue_task(next, array);
+
+ /*
+ * We may have just been demoted below other
+ * runnable tasks in our previous queue.
+ */
+ next->sleep_type = SLEEP_NORMAL;
+ goto repeat_selection;
+ }
}
- next->activated = 0;
+ next->sleep_type = SLEEP_NORMAL;
switch_tasks:
if (next == rq->idle)
schedstat_inc(rq, sched_goidle);
@@ -3118,6 +3401,14 @@
prev->sleep_avg = 0;
prev->timestamp = prev->last_ran = now;
+ /*
+ * Tag start of execution of a new timeslice.
+ */
+ if (unlikely(slice_is_new(next))) {
+ next->last_slice = jiffies;
+ clr_slice_is_new(next);
+ }
+
sched_info_switch(prev, next);
if (likely(prev != next)) {
next->timestamp = now;
--- linux-2.6.16-rc1/kernel/sysctl.c.org 2006-02-12 21:29:24.000000000 +0100
+++ linux-2.6.16-rc1/kernel/sysctl.c 2006-02-12 21:29:53.000000000 +0100
@@ -71,6 +71,8 @@
extern int pid_max_min, pid_max_max;
extern int sysctl_drop_caches;
extern int percpu_pagelist_fraction;
+extern int sched_g1;
+extern int sched_g2;
#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)
int unknown_nmi_panic;
@@ -226,6 +228,11 @@
{ .ctl_name = 0 }
};
+/* Constants for minimum and maximum testing in vm_table and
+ * kern_table. We use these as one-element integer vectors. */
+static int zero;
+static int one_hundred = 100;
+
static ctl_table kern_table[] = {
{
.ctl_name = KERN_OSTYPE,
@@ -658,15 +665,29 @@
.proc_handler = &proc_dointvec,
},
#endif
+ {
+ .ctl_name = KERN_SCHED_THROTTLE1,
+ .procname = "sched_g1",
+ .data = &sched_g1,
+ .maxlen = sizeof (int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ .strategy = &sysctl_intvec,
+ .extra1 = &zero,
+ },
+ {
+ .ctl_name = KERN_SCHED_THROTTLE2,
+ .procname = "sched_g2",
+ .data = &sched_g2,
+ .maxlen = sizeof (int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ .strategy = &sysctl_intvec,
+ .extra1 = &zero,
+ },
{ .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,
--- linux-2.6.16-rc1/fs/pipe.c.org 2006-02-12 21:29:35.000000000 +0100
+++ linux-2.6.16-rc1/fs/pipe.c 2006-02-12 21:29:53.000000000 +0100
@@ -39,11 +39,7 @@
{
DEFINE_WAIT(wait);
- /*
- * Pipes are system-local resources, so sleeping on them
- * is considered a noninteractive wait:
- */
- prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE|TASK_NONINTERACTIVE);
+ prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE);
mutex_unlock(PIPE_MUTEX(*inode));
schedule();
finish_wait(PIPE_WAIT(*inode), &wait);
-
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