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Commit 0cda4c02 authored by Yan, Zheng's avatar Yan, Zheng Committed by Ingo Molnar
Browse files

perf: Introduce perf_pmu_migrate_context() 



Originally from Peter Zijlstra. The helper migrates perf events
from one cpu to another cpu.

Signed-off-by: default avatarZheng Yan <zheng.z.yan@intel.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1339741902-8449-5-git-send-email-zheng.z.yan@intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e2d37cd2

include/linux/perf_event.h

+2 −0
Original line number Diff line number Diff line
@@ -1107,6 +1107,8 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, 
				struct task_struct *task,

				perf_overflow_handler_t callback,

				void *context);

extern void perf_pmu_migrate_context(struct pmu *pmu,

				int src_cpu, int dst_cpu);

extern u64 perf_event_read_value(struct perf_event *event,

				 u64 *enabled, u64 *running);

kernel/events/core.c

+36 −0
Original line number Diff line number Diff line
@@ -1645,6 +1645,8 @@ perf_install_in_context(struct perf_event_context *ctx, 
	lockdep_assert_held(&ctx->mutex);



	event->ctx = ctx;

	if (event->cpu != -1)

		event->cpu = cpu;



	if (!task) {

		/*
@@ -6379,6 +6381,7 @@ SYSCALL_DEFINE5(perf_event_open, 
	mutex_lock(&ctx->mutex);



	if (move_group) {

		synchronize_rcu();

		perf_install_in_context(ctx, group_leader, event->cpu);

		get_ctx(ctx);

		list_for_each_entry(sibling, &group_leader->sibling_list,
@@ -6484,6 +6487,39 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, 
}

EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);



void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu)

{

	struct perf_event_context *src_ctx;

	struct perf_event_context *dst_ctx;

	struct perf_event *event, *tmp;

	LIST_HEAD(events);



	src_ctx = &per_cpu_ptr(pmu->pmu_cpu_context, src_cpu)->ctx;

	dst_ctx = &per_cpu_ptr(pmu->pmu_cpu_context, dst_cpu)->ctx;



	mutex_lock(&src_ctx->mutex);

	list_for_each_entry_safe(event, tmp, &src_ctx->event_list,

				 event_entry) {

		perf_remove_from_context(event);

		put_ctx(src_ctx);

		list_add(&event->event_entry, &events);

	}

	mutex_unlock(&src_ctx->mutex);



	synchronize_rcu();



	mutex_lock(&dst_ctx->mutex);

	list_for_each_entry_safe(event, tmp, &events, event_entry) {

		list_del(&event->event_entry);

		if (event->state >= PERF_EVENT_STATE_OFF)

			event->state = PERF_EVENT_STATE_INACTIVE;

		perf_install_in_context(dst_ctx, event, dst_cpu);

		get_ctx(dst_ctx);

	}

	mutex_unlock(&dst_ctx->mutex);

}

EXPORT_SYMBOL_GPL(perf_pmu_migrate_context);



static void sync_child_event(struct perf_event *child_event,

			       struct task_struct *child)

{