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perf: Fix cgroup event scheduling

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There appears to be a problem in __perf_event_task_sched_in() wrt
cgroup event scheduling.

The normal event scheduling order is:

	CPU pinned
	Task pinned
	CPU flexible
	Task flexible

And since perf_cgroup_sched*() only schedules the cpu context, we must
call this _before_ adding the task events.

Note: double check what happens on the ctx switch optimization where
the task ctx isn't scheduled.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-01-08 09:21:40 +01:00 committed by Ingo Molnar
parent c994d61367
commit 7e41d17753
1 changed files with 10 additions and 7 deletions
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17
kernel/events/core.c
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@ -2806,6 +2806,16 @@ void __perf_event_task_sched_in(struct task_struct *prev,
struct perf_event_context *ctx;
int ctxn;
/*
* If cgroup events exist on this CPU, then we need to check if we have
* to switch in PMU state; cgroup event are system-wide mode only.
*
* Since cgroup events are CPU events, we must schedule these in before
* we schedule in the task events.
*/
if (atomic_read(this_cpu_ptr(&perf_cgroup_events)))
perf_cgroup_sched_in(prev, task);
for_each_task_context_nr(ctxn) {
ctx = task->perf_event_ctxp[ctxn];
if (likely(!ctx))
@ -2813,13 +2823,6 @@ void __perf_event_task_sched_in(struct task_struct *prev,
perf_event_context_sched_in(ctx, task);
}
/*
* if cgroup events exist on this CPU, then we need
* to check if we have to switch in PMU state.
* cgroup event are system-wide mode only
*/
if (atomic_read(this_cpu_ptr(&perf_cgroup_events)))
perf_cgroup_sched_in(prev, task);
if (atomic_read(&nr_switch_events))
perf_event_switch(task, prev, true);