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sched: disable forced preemption by default 

Implement feature bit to disable forced preemption. This way
it can be checked whether a workload is overscheduling or not.

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 2007-10-15 17:00:14 +02:00 committed by Ingo Molnar
parent e62dd02ed0
commit ce6c131131
2 changed files with 17 additions and 13 deletions
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4
kernel/sched.c
View File

@ -444,13 +444,15 @@ enum {
SCHED_FEAT_START_DEBIT = 2,
SCHED_FEAT_TREE_AVG = 4,
SCHED_FEAT_APPROX_AVG = 8,
SCHED_FEAT_WAKEUP_PREEMPT = 16,
};
const_debug unsigned int sysctl_sched_features =
SCHED_FEAT_NEW_FAIR_SLEEPERS *1 |
SCHED_FEAT_START_DEBIT *1 |
SCHED_FEAT_TREE_AVG *0 |
SCHED_FEAT_APPROX_AVG *0;
SCHED_FEAT_APPROX_AVG *0 |
SCHED_FEAT_WAKEUP_PREEMPT *1;
#define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x)

26
kernel/sched_fair.c
View File

@ -626,7 +626,7 @@ static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
*/
update_curr(cfs_rq);
if (cfs_rq->nr_running > 1)
if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
check_preempt_tick(cfs_rq, curr);
}
@ -828,18 +828,20 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
return;
}
while (!is_same_group(se, pse)) {
se = parent_entity(se);
pse = parent_entity(pse);
if (sched_feat(WAKEUP_PREEMPT)) {
while (!is_same_group(se, pse)) {
se = parent_entity(se);
pse = parent_entity(pse);
}
delta = se->vruntime - pse->vruntime;
gran = sysctl_sched_wakeup_granularity;
if (unlikely(se->load.weight != NICE_0_LOAD))
gran = calc_delta_fair(gran, &se->load);
if (delta > gran)
resched_task(curr);
}
delta = se->vruntime - pse->vruntime;
gran = sysctl_sched_wakeup_granularity;
if (unlikely(se->load.weight != NICE_0_LOAD))
gran = calc_delta_fair(gran, &se->load);
if (delta > gran)
resched_task(curr);
}
static struct task_struct *pick_next_task_fair(struct rq *rq)