Commit 9b33fa6b authored Mar 10, 2010 by eranian@google.com Committed by Ingo Molnar Mar 11, 2010

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@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268288765-5326-1-git-send-email-eranian@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent caa0142d

kernel/perf_event.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -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)

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