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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2007-10-15 17:00:14 +0200
committerIngo Molnar <mingo@elte.hu>2007-10-15 17:00:14 +0200
commitce6c131131df442f0d49d064129ecc52d9fe8ca9 (patch)
tree14b93a32144e7270dd821901ff247f506270a3a3 /kernel
parente62dd02ed0af35631c6ca473e50758c9594773cf (diff)
downloadlinux-ce6c131131df442f0d49d064129ecc52d9fe8ca9.tar.bz2
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c4
-rw-r--r--kernel/sched_fair.c24
2 files changed, 16 insertions, 12 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index b7dff36c7c8c..0bd8f2c0fb40 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -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)
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 3ac096e74faf..3843ec71aad5 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -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);
+ 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);
+ if (delta > gran)
+ resched_task(curr);
+ }
}
static struct task_struct *pick_next_task_fair(struct rq *rq)