Messages in this thread | | | Date | Fri, 24 Jun 2011 08:44:19 -0400 | From | Eric B Munson <> | Subject | Re: [PATCH 3/3] events: Ensure that timers are updated without requiring read() call |
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On Fri, 24 Jun 2011, Peter Zijlstra wrote:
> On Thu, 2011-06-23 at 16:34 -0400, Eric B Munson wrote: > > The event tracing infrastructure exposes two timers which should be updated > > each time the value of the counter is updated. Currently, these counters are > > only updated when userspace calls read() on the fd associated with an event. > > This means that counters which are read via the mmap'd page exclusively never > > have their timers updated. This patch adds ensures that the timers are updated > > each time the values in the mmap'd page are updated. > > > > Signed-off-by: Eric B Munson <emunson@mgebm.net> > > --- > > kernel/events/core.c | 12 ++++++++++++ > > 1 files changed, 12 insertions(+), 0 deletions(-) > > > > diff --git a/kernel/events/core.c b/kernel/events/core.c > > index 9e9a7fa..e3be175 100644 > > --- a/kernel/events/core.c > > +++ b/kernel/events/core.c > > @@ -3382,6 +3382,18 @@ void perf_event_update_userpage(struct perf_event *event) > > struct perf_buffer *buffer; > > > > rcu_read_lock(); > > + /* > > + * compute total_time_enabled, total_time_running > > + * based on snapshot values taken when the event > > + * was last scheduled in. > > + * > > + * we cannot simply called update_context_time() > > + * because of locking issue as we are called in > > s/are/can be/ > > > + * NMI context > > + */ > > + calc_timer_values(event, > > + &event->total_time_enabled, > > + &event->total_time_running); > > I'm not sure writing those from NMI context is a sane thing to do, best > is to compute the values into a local variable and use that variable > below. > > Took the first two patches. >
Thanks, I will send out an updated patch once I get it tested.
Eric [unhandled content-type:application/pgp-signature] | |