perf: Optimize ctx_sched_out()
Oleg noted that ctx_sched_out() disables the PMU even though it might
not actually do something, avoid needless PMU-disabling.
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110409192141.665385503@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/events/core.c b/kernel/events/core.c
index d863b3c..4d9a1f01 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1760,7 +1760,6 @@
struct perf_event *event;
raw_spin_lock(&ctx->lock);
- perf_pmu_disable(ctx->pmu);
ctx->is_active = 0;
if (likely(!ctx->nr_events))
goto out;
@@ -1770,6 +1769,7 @@
if (!ctx->nr_active)
goto out;
+ perf_pmu_disable(ctx->pmu);
if (event_type & EVENT_PINNED) {
list_for_each_entry(event, &ctx->pinned_groups, group_entry)
group_sched_out(event, cpuctx, ctx);
@@ -1779,8 +1779,8 @@
list_for_each_entry(event, &ctx->flexible_groups, group_entry)
group_sched_out(event, cpuctx, ctx);
}
-out:
perf_pmu_enable(ctx->pmu);
+out:
raw_spin_unlock(&ctx->lock);
}