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Commit 9b33fa6b authored by eranian@google.com's avatar eranian@google.com Committed by Ingo Molnar
Browse files

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: default avatarStephane Eranian <eranian@google.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268288765-5326-1-git-send-email-eranian@google.com>
Signed-off-by: default avatarIngo 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)