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Commit 6fcf8774 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
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Revert "perf/cgroups: Don't rotate events for cgroups unnecessarily" 



This reverts commit 0b4c9255 as it
breaks the abi.

Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
Change-Id: I3a4cbfa1cfbef15a6aaabf759dc2bbfaa8f2b47a
parent 5e002cfc

include/linux/perf_event.h

+0 −5
Original line number Diff line number Diff line
@@ -761,11 +761,6 @@ struct perf_event_context { 
	int				nr_stat;

	int				nr_freq;

	int				rotate_disable;

	/*

	 * Set when nr_events != nr_active, except tolerant to events not

	 * necessary to be active due to scheduling constraints, such as cgroups.

	 */

	int				rotate_necessary;

	atomic_t			refcount;

	struct task_struct		*task;

kernel/events/core.c

+20 −22
Original line number Diff line number Diff line
@@ -2952,12 +2952,6 @@ static void ctx_sched_out(struct perf_event_context *ctx, 
	if (!ctx->nr_active || !(is_active & EVENT_ALL))

		return;



	/*

	 * If we had been multiplexing, no rotations are necessary, now no events

	 * are active.

	 */

	ctx->rotate_necessary = 0;



	perf_pmu_disable(ctx->pmu);

	if (is_active & EVENT_PINNED) {

		list_for_each_entry_safe(event, tmp, &ctx->pinned_active, active_list)
@@ -3325,13 +3319,10 @@ static int flexible_sched_in(struct perf_event *event, void *data) 
		return 0;



	if (group_can_go_on(event, sid->cpuctx, sid->can_add_hw)) {

		int ret = group_sched_in(event, sid->cpuctx, sid->ctx);

		if (ret) {

			sid->can_add_hw = 0;

			sid->ctx->rotate_necessary = 1;

			return 0;

		}

		if (!group_sched_in(event, sid->cpuctx, sid->ctx))

			list_add_tail(&event->active_list, &sid->ctx->flexible_active);

		else

			sid->can_add_hw = 0;

	}



	return 0;
@@ -3699,17 +3690,24 @@ ctx_first_active(struct perf_event_context *ctx) 
static bool perf_rotate_context(struct perf_cpu_context *cpuctx)

{

	struct perf_event *cpu_event = NULL, *task_event = NULL;

	struct perf_event_context *task_ctx = NULL;

	int cpu_rotate, task_rotate;

	bool cpu_rotate = false, task_rotate = false;

	struct perf_event_context *ctx = NULL;



	/*

	 * Since we run this from IRQ context, nobody can install new

	 * events, thus the event count values are stable.

	 */



	cpu_rotate = cpuctx->ctx.rotate_necessary;

	task_ctx = cpuctx->task_ctx;

	task_rotate = task_ctx ? task_ctx->rotate_necessary : 0;

	if (cpuctx->ctx.nr_events) {

		if (cpuctx->ctx.nr_events != cpuctx->ctx.nr_active)

			cpu_rotate = true;

	}



	ctx = cpuctx->task_ctx;

	if (ctx && ctx->nr_events) {

		if (ctx->nr_events != ctx->nr_active)

			task_rotate = true;

	}



	if (!(cpu_rotate || task_rotate))

		return false;
@@ -3718,7 +3716,7 @@ static bool perf_rotate_context(struct perf_cpu_context *cpuctx) 
	perf_pmu_disable(cpuctx->ctx.pmu);



	if (task_rotate)

		task_event = ctx_first_active(task_ctx);

		task_event = ctx_first_active(ctx);

	if (cpu_rotate)

		cpu_event = ctx_first_active(&cpuctx->ctx);
@@ -3726,17 +3724,17 @@ static bool perf_rotate_context(struct perf_cpu_context *cpuctx) 
	 * As per the order given at ctx_resched() first 'pop' task flexible

	 * and then, if needed CPU flexible.

	 */

	if (task_event || (task_ctx && cpu_event))

		ctx_sched_out(task_ctx, cpuctx, EVENT_FLEXIBLE);

	if (task_event || (ctx && cpu_event))

		ctx_sched_out(ctx, cpuctx, EVENT_FLEXIBLE);

	if (cpu_event)

		cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);



	if (task_event)

		rotate_ctx(task_ctx, task_event);

		rotate_ctx(ctx, task_event);

	if (cpu_event)

		rotate_ctx(&cpuctx->ctx, cpu_event);



	perf_event_sched_in(cpuctx, task_ctx, current);

	perf_event_sched_in(cpuctx, ctx, current);



	perf_pmu_enable(cpuctx->ctx.pmu);

	perf_ctx_unlock(cpuctx, cpuctx->task_ctx);