From e69b0f1b41c0e57bb1e29100b5810a5914efcb45 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 15 Sep 2009 19:38:52 +0200 Subject: sched: Add a few SYNC hint knobs to play with Currently we use overlap to weaken the SYNC hint, but allow it to set the hint as well. echo NO_SYNC_WAKEUP > /debug/sched_features echo SYNC_MORE > /debug/sched_features preserves pipe-test behaviour without using the WF_SYNC hint. Worth playing with on more workloads... Signed-off-by: Peter Zijlstra LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/sched_fair.c | 14 +++++++++++--- kernel/sched_features.h | 10 ++++++++++ 2 files changed, 21 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 6766959c7f4..280892e9d85 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1165,9 +1165,17 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) load = source_load(prev_cpu, idx); this_load = target_load(this_cpu, idx); - if (sync && (curr->se.avg_overlap > sysctl_sched_migration_cost || - p->se.avg_overlap > sysctl_sched_migration_cost)) - sync = 0; + if (sync) { + if (sched_feat(SYNC_LESS) && + (curr->se.avg_overlap > sysctl_sched_migration_cost || + p->se.avg_overlap > sysctl_sched_migration_cost)) + sync = 0; + } else { + if (sched_feat(SYNC_MORE) && + (curr->se.avg_overlap < sysctl_sched_migration_cost && + p->se.avg_overlap < sysctl_sched_migration_cost)) + sync = 1; + } /* * If sync wakeup then subtract the (maximum possible) diff --git a/kernel/sched_features.h b/kernel/sched_features.h index 294e10edd3c..70115c69c7a 100644 --- a/kernel/sched_features.h +++ b/kernel/sched_features.h @@ -62,6 +62,16 @@ SCHED_FEAT(SYNC_WAKEUPS, 1) */ SCHED_FEAT(AFFINE_WAKEUPS, 1) +/* + * Weaken SYNC hint based on overlap + */ +SCHED_FEAT(SYNC_LESS, 1) + +/* + * Add SYNC hint based on overlap + */ +SCHED_FEAT(SYNC_MORE, 0) + /* * Prefer to schedule the task we woke last (assuming it failed * wakeup-preemption), since its likely going to consume data we -- cgit v1.2.3