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Commit 44377277 authored by Alexander Shishkin's avatar Alexander Shishkin Committed by Ingo Molnar
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perf: Disable all pmus on unthrottling and rescheduling 



Currently, only one PMU in a context gets disabled during unthrottling
and event_sched_{out,in}(), however, events in one context may belong to
different pmus, which results in PMUs being reprogrammed while they are
still enabled.

This means that mixed PMU use [which is rare in itself] resulted in
potentially completely unreliable results: corrupted events, bogus
results, etc.

This patch temporarily disables PMUs that correspond to
each event in the context while these events are being modified.

Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: default avatarAndi Kleen <ak@linux.intel.com>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Link: http://lkml.kernel.org/r/1387196256-8030-1-git-send-email-alexander.shishkin@linux.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent cf30d52e

kernel/events/core.c

+18 −3
Original line number Diff line number Diff line
@@ -1396,6 +1396,8 @@ event_sched_out(struct perf_event *event, 
	if (event->state != PERF_EVENT_STATE_ACTIVE)

		return;



	perf_pmu_disable(event->pmu);



	event->state = PERF_EVENT_STATE_INACTIVE;

	if (event->pending_disable) {

		event->pending_disable = 0;
@@ -1412,6 +1414,8 @@ event_sched_out(struct perf_event *event, 
		ctx->nr_freq--;

	if (event->attr.exclusive || !cpuctx->active_oncpu)

		cpuctx->exclusive = 0;



	perf_pmu_enable(event->pmu);

}



static void
@@ -1652,6 +1656,7 @@ event_sched_in(struct perf_event *event, 
		 struct perf_event_context *ctx)

{

	u64 tstamp = perf_event_time(event);

	int ret = 0;



	if (event->state <= PERF_EVENT_STATE_OFF)

		return 0;
@@ -1674,10 +1679,13 @@ event_sched_in(struct perf_event *event, 
	 */

	smp_wmb();



	perf_pmu_disable(event->pmu);



	if (event->pmu->add(event, PERF_EF_START)) {

		event->state = PERF_EVENT_STATE_INACTIVE;

		event->oncpu = -1;

		return -EAGAIN;

		ret = -EAGAIN;

		goto out;

	}



	event->tstamp_running += tstamp - event->tstamp_stopped;
@@ -1693,7 +1701,10 @@ event_sched_in(struct perf_event *event, 
	if (event->attr.exclusive)

		cpuctx->exclusive = 1;



	return 0;

out:

	perf_pmu_enable(event->pmu);



	return ret;

}



static int
@@ -2743,6 +2754,8 @@ static void perf_adjust_freq_unthr_context(struct perf_event_context *ctx, 
		if (!event_filter_match(event))

			continue;



		perf_pmu_disable(event->pmu);



		hwc = &event->hw;



		if (hwc->interrupts == MAX_INTERRUPTS) {
@@ -2752,7 +2765,7 @@ static void perf_adjust_freq_unthr_context(struct perf_event_context *ctx, 
		}



		if (!event->attr.freq || !event->attr.sample_freq)

			continue;

			goto next;



		/*

		 * stop the event and update event->count
@@ -2774,6 +2787,8 @@ static void perf_adjust_freq_unthr_context(struct perf_event_context *ctx, 
			perf_adjust_period(event, period, delta, false);



		event->pmu->start(event, delta > 0 ? PERF_EF_RELOAD : 0);

	next:

		perf_pmu_enable(event->pmu);

	}



	perf_pmu_enable(ctx->pmu);