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authorPeter Zijlstra <peterz@infradead.org>2009-11-23 15:00:36 +0100
committerIngo Molnar <mingo@elte.hu>2009-11-23 15:22:19 +0100
commitacd1d7c1f8f3d848a3c5327dc09f8c1efb971678 (patch)
tree88ec283110f78cf803c71a3d1d919a422f2f13c5
parent4ed7c92d68a5387ba5f7030dc76eab03558e27f5 (diff)
downloadop-kernel-dev-acd1d7c1f8f3d848a3c5327dc09f8c1efb971678.zip
op-kernel-dev-acd1d7c1f8f3d848a3c5327dc09f8c1efb971678.tar.gz
perf_events: Restore sanity to scaling land
It is quite possible to call update_event_times() on a context that isn't actually running and thereby confuse the thing. perf stat was reporting !100% scale values for software counters (2e2af50b perf_events: Disable events when we detach them, solved the worst of that, but there was still some left). The thing that happens is that because we are not self-reaping (we have a caring parent) there is a time between the last schedule (out) and having do_exit() called which will detach the events. This period would be accounted as enabled,!running because the event->state==INACTIVE, even though !event->ctx->is_active. Similar issues could have been observed by calling read() on a event while the attached task was not scheduled in. Solve this by teaching update_event_times() about ctx->is_active. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <1258984836.4531.480.camel@laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/perf_event.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 0b0d5f7..0aafe85 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -274,7 +274,12 @@ static void update_event_times(struct perf_event *event)
event->group_leader->state < PERF_EVENT_STATE_INACTIVE)
return;
- event->total_time_enabled = ctx->time - event->tstamp_enabled;
+ if (ctx->is_active)
+ run_end = ctx->time;
+ else
+ run_end = event->tstamp_stopped;
+
+ event->total_time_enabled = run_end - event->tstamp_enabled;
if (event->state == PERF_EVENT_STATE_INACTIVE)
run_end = event->tstamp_stopped;
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