perf: Add perf_event::child_count

Only child counters adding back their values into the parent counter
are responsible for cross-cpu updates to event->count.

So if we pull that out into a new child_count variable, we get an
event->count that is only modified locally.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 441992a9775c..f34dab9b275e 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -671,6 +671,7 @@ struct perf_event {
         enum perf_event_active_state    state;
         unsigned int                    attach_state;
         atomic64_t                      count;
+        atomic64_t                      child_count;
 
         /*
          * These are the total time in nanoseconds that the event