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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-09-15 19:38:52 +0200
committerIngo Molnar <mingo@elte.hu>2009-09-15 19:47:23 +0200
commite69b0f1b41c0e57bb1e29100b5810a5914efcb45 (patch)
treeded9f35988e907c1b9cf45cd2f536b920f5f65b7
parent63859d4fe4c97b737e7adbfe60acb1c2b2e668cb (diff)
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 <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/sched_fair.c14
-rw-r--r--kernel/sched_features.h10
2 files changed, 21 insertions, 3 deletions
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
@@ -63,6 +63,16 @@ 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
* touched, increases cache locality.