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| author | Peter Zijlstra <peterz@infradead.org> | 2013-08-02 21:16:30 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-08-16 17:55:52 +0200 |
| commit | 5ec4c599a52362896c3e7c6a31ba6145dca9c6f5 (patch) | |
| tree | 840686d157743f4e255eac2162cf57579bd98953 /kernel/events | |
| parent | 948b26b6ddd08a57cb95ebb0dc96fde2edd5c383 (diff) | |
| download | blackbird-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.c | 8 |
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. |
