Commit-ID: 7e41d17753e6e0da55d343997454dd4fbe8d28a8
Gitweb: http://git.kernel.org/tip/7e41d17753e6e0da55d343997454dd4fbe8d28a8
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 8 Jan 2016 09:21:40 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 21 Jan 2016 18:54:19 +0100
perf: Fix cgroup event scheduling
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@xxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/events/core.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index c77b05d..9d1195a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -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);
--
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