[tip:perf/core] perf: Add perf_event::child_count

tip-bot for Peter Zijlstra
2010-06-09T10:18:17Z

Commit-ID: a6e6dea68c18f705957573ee5596097c7e82d0e5
Gitweb: http://git.kernel.org/tip/a6e6dea68c18f705957573ee5596097c7e82d0e5
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Fri, 21 May 2010 14:27:58 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 9 Jun 2010 11:12:37 +0200

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>
---
include/linux/perf_event.h | 1 +
kernel/perf_event.c | 4 ++--
2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 441992a..f34dab9 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
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index ab4c0ff..a395fda 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -1738,7 +1738,7 @@ static void __perf_event_read(void *info)

static inline u64 perf_event_count(struct perf_event *event)
{
- return atomic64_read(&event->count);
+ return atomic64_read(&event->count) + atomic64_read(&event->child_count);
}

static u64 perf_event_read(struct perf_event *event)
@@ -5379,7 +5379,7 @@ static void sync_child_event(struct perf_event *child_event,
/*
* Add back the child's count to the parent's count:
*/
- atomic64_add(child_val, &parent_event->count);
+ atomic64_add(child_val, &parent_event->child_count);
atomic64_add(child_event->total_time_enabled,
&parent_event->child_total_time_enabled);
atomic64_add(child_event->total_time_running,