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authorPeter Zijlstra <peterz@infradead.org>2013-08-02 21:16:30 +0200
committerIngo Molnar <mingo@kernel.org>2013-08-16 17:55:52 +0200
commit5ec4c599a52362896c3e7c6a31ba6145dca9c6f5 (patch)
tree840686d157743f4e255eac2162cf57579bd98953 /kernel/events
parent948b26b6ddd08a57cb95ebb0dc96fde2edd5c383 (diff)
downloadblackbird-op-linux-5ec4c599a52362896c3e7c6a31ba6145dca9c6f5.tar.gz
blackbird-op-linux-5ec4c599a52362896c3e7c6a31ba6145dca9c6f5.zip
perf: Do not compute time values unnecessarily
We should not be calling calc_timer_values() for events that do not actually have an mmap()'ed userpage. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20130802191630.GT27162@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2e675e830976..928fae7ca8c7 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3670,6 +3670,10 @@ void perf_event_update_userpage(struct perf_event *event)
u64 enabled, running, now;
rcu_read_lock();
+ rb = rcu_dereference(event->rb);
+ if (!rb)
+ goto unlock;
+
/*
* compute total_time_enabled, total_time_running
* based on snapshot values taken when the event
@@ -3680,12 +3684,8 @@ void perf_event_update_userpage(struct perf_event *event)
* NMI context
*/
calc_timer_values(event, &now, &enabled, &running);
- rb = rcu_dereference(event->rb);
- if (!rb)
- goto unlock;
userpg = rb->user_page;
-
/*
* Disable preemption so as to not let the corresponding user-space
* spin too long if we get preempted.
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