Commit-ID: 5ec4c599a52362896c3e7c6a31ba6145dca9c6f5 Gitweb: http://git.kernel.org/tip/5ec4c599a52362896c3e7c6a31ba6145dca9c6f5 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Fri, 2 Aug 2013 21:16:30 +0200 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Fri, 16 Aug 2013 17:55:52 +0200 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@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20130802191630.GT27162@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/events/core.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 2e675e8..928fae7 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. -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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