Messages in this thread | | | Subject | Re: [BUG] perf_event: when events are grouped, the time enabled / running values are incorrect | From | Peter Zijlstra <> | Date | Tue, 11 May 2010 22:27:51 +0200 |
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On Tue, 2010-05-11 at 22:23 +0200, Stephane Eranian wrote: > On Tue, May 11, 2010 at 10:11 PM, Peter Zijlstra <peterz@infradead.org> wrote: > > On Tue, 2010-05-11 at 21:55 +0200, stephane eranian wrote: > >> Events are also grouped in this example. Both this same issue exists > >> also when only > >> one event is used. I suspect an update_event_times() or > >> update_group_times() is also > >> missing on the sampling path in perf_overflow_handler(). > > > > Hrmm, you're right, except fixing that is non-trivial. > > update_event_times() wants to be called with ctx->lock held and we can't > > do that from NMI context. > > > Why do you need the lock when the event is running on a CPU in NMI context? > What action issued remotely could modify the data used by this function without > the need for IPI?
Not sure, would at the very least have to verify that. I'll try and have a look.
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