diff options
| author | leilei.lin <[email protected]> | 2017-08-09 08:29:21 +0800 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2017-08-10 12:08:40 +0200 |
| commit | fdccc3fb7a42ea4e4cd77d2fb8fa3a45c66ec0bf (patch) | |
| tree | 0bc643ab390edab5ded23a9fd381f058425a8438 | |
| parent | ab027620e95987b5f0145013090a109b4152d23b (diff) | |
perf/core: Reduce context switch overhead
Skip most of the PMU context switching overhead when ctx->nr_events is 0.
50% performance overhead was observed under an extreme testcase.
Signed-off-by: leilei.lin <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
[ Rewrote the changelog. ]
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | kernel/events/core.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index ee20d4c546b5..d704e23914bf 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3211,6 +3211,13 @@ static void perf_event_context_sched_in(struct perf_event_context *ctx, return; perf_ctx_lock(cpuctx, ctx); + /* + * We must check ctx->nr_events while holding ctx->lock, such + * that we serialize against perf_install_in_context(). + */ + if (!ctx->nr_events) + goto unlock; + perf_pmu_disable(ctx->pmu); /* * We want to keep the following priority order: @@ -3224,6 +3231,8 @@ static void perf_event_context_sched_in(struct perf_event_context *ctx, cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE); perf_event_sched_in(cpuctx, ctx, task); perf_pmu_enable(ctx->pmu); + +unlock: perf_ctx_unlock(cpuctx, ctx); } |