[tip:perf/core] perf_events: Improve task_sched_in()
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From: tip-bot for eranian on 11 Mar 2010 09:50 Commit-ID: 9b33fa6ba0e2f90fdf407501db801c2511121564 Gitweb: http://git.kernel.org/tip/9b33fa6ba0e2f90fdf407501db801c2511121564 Author: eranian(a)google.com <eranian(a)google.com> AuthorDate: Wed, 10 Mar 2010 22:26:05 -0800 Committer: Ingo Molnar <mingo(a)elte.hu> CommitDate: Thu, 11 Mar 2010 15:23:28 +0100 perf_events: Improve task_sched_in() This patch is an optimization in perf_event_task_sched_in() to avoid scheduling the events twice in a row. Without it, the perf_disable()/perf_enable() pair is invoked twice, thereby pinned events counts while scheduling flexible events and we go throuh hw_perf_enable() twice. By encapsulating, the whole sequence into perf_disable()/perf_enable() we ensure, hw_perf_enable() is going to be invoked only once because of the refcount protection. Signed-off-by: Stephane Eranian <eranian(a)google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra(a)chello.nl> LKML-Reference: <1268288765-5326-1-git-send-email-eranian(a)google.com> Signed-off-by: Ingo Molnar <mingo(a)elte.hu> --- kernel/perf_event.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 52c69a3..3853d49 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -1368,6 +1368,8 @@ void perf_event_task_sched_in(struct task_struct *task) if (cpuctx->task_ctx == ctx) return; + perf_disable(); + /* * We want to keep the following priority order: * cpu pinned (that don't need to move), task pinned, @@ -1380,6 +1382,8 @@ void perf_event_task_sched_in(struct task_struct *task) ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE); cpuctx->task_ctx = ctx; + + perf_enable(); } #define MAX_INTERRUPTS (~0ULL) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |