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sched: SCHED_OTHER vs SCHED_IDLE isolation

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Stronger SCHED_IDLE isolation:

 - no SCHED_IDLE buddies
 - never let SCHED_IDLE preempt on wakeup
 - always preempt SCHED_IDLE on wakeup
 - limit SLEEPER fairness for SCHED_IDLE.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-01-15 14:53:38 +01:00 committed by Ingo Molnar
parent cce7ade803
commit 6bc912b71b
1 changed files with 22 additions and 8 deletions
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30
kernel/sched_fair.c
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@ -677,9 +677,13 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
unsigned long thresh = sysctl_sched_latency;
/*
* convert the sleeper threshold into virtual time
* Convert the sleeper threshold into virtual time.
* SCHED_IDLE is a special sub-class. We care about
* fairness only relative to other SCHED_IDLE tasks,
* all of which have the same weight.
*/
if (sched_feat(NORMALIZED_SLEEPER))
if (sched_feat(NORMALIZED_SLEEPER) &&
task_of(se)->policy != SCHED_IDLE)
thresh = calc_delta_fair(thresh, se);
vruntime -= thresh;
@ -1340,14 +1344,18 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
static void set_last_buddy(struct sched_entity *se)
{
for_each_sched_entity(se)
cfs_rq_of(se)->last = se;
if (likely(task_of(se)->policy != SCHED_IDLE)) {
for_each_sched_entity(se)
cfs_rq_of(se)->last = se;
}
}
static void set_next_buddy(struct sched_entity *se)
{
for_each_sched_entity(se)
cfs_rq_of(se)->next = se;
if (likely(task_of(se)->policy != SCHED_IDLE)) {
for_each_sched_entity(se)
cfs_rq_of(se)->next = se;
}
}
/*
@ -1393,12 +1401,18 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
return;
/*
* Batch tasks do not preempt (their preemption is driven by
* Batch and idle tasks do not preempt (their preemption is driven by
* the tick):
*/
if (unlikely(p->policy == SCHED_BATCH))
if (unlikely(p->policy != SCHED_NORMAL))
return;
/* Idle tasks are by definition preempted by everybody. */
if (unlikely(curr->policy == SCHED_IDLE)) {
resched_task(curr);
return;
}
if (!sched_feat(WAKEUP_PREEMPT))
return;