Messages in this thread | | | Subject | Re: [PATCH v6 2/3]: perf/core: use context tstamp_data for skipped events on mux interrupt | From | Alexey Budankov <> | Date | Fri, 4 Aug 2017 17:23:35 +0300 |
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On 04.08.2017 15:35, Peter Zijlstra wrote: > On Thu, Aug 03, 2017 at 09:47:56PM +0300, Alexey Budankov wrote: >> On 03.08.2017 18:00, Peter Zijlstra wrote: > >>> Are the magic spots, right? And I'm not convinced its right. >>> >>> Suppose I have two events in my context, and I created them 1 minute >>> apart. Then their respective tstamp_enabled are 1 minute apart as well. >>> But the above doesn't seem to preserve that difference. >>> >>> A similar argument can be made for running I think. That is a per event >>> value and cannot be passed along to the ctx and back. >> >> Aww, I see your point and it challenges my initial assumptions. >> Let me think thru the case more. There must be some solution. Thanks! > > So the sensible thing is probably to rewrite the entire time tracking to > make more sense. OTOH that's also the riskiest. > > Something like: > > __update_state_and_time(event, new_state) > { > u64 delta, now = perf_event_time(event); > int old_state = event->state; > > event->tstamp = now; > event->state = new_state; > > delta = now - event->tstamp; > switch (state) { > case STATE_ACTIVE: > WARN_ON_ONCE(old_state != STATE_INACTIVE); > event->total_time_enabled += delta; > break; > > case STATE_INACTIVE: > switch (old_state) { > case STATE_OFF: > /* ignore the OFF -> INACTIVE period */ > break; > > case STATE_ACTIVE: > event->total_time_enabled += delta; > event->total_time_running += delta; > break; > > default: > WARN_ONCE(); > } > break; > > case STATE_OFF: > WARN_ON_ONCE(old_state != STATE_INACTIVE) > event->total_time_enabled += delta; > break; > } > } > > __read_curent_times(event, u64 *enabled, u64 *running) > { > u64 delta, now = perf_event_time(event); > > delta = now - event->tstamp; > > *enabled = event->total_time_enabled; > if (event->state >= STATE_INACTIVE) > *enabled += delta; > *running = event->total_time_running > if (event->state == STATE_ACTIVE) > *running += delta; > } > > perhaps? That instantly solves the problem I think, because now we don't > need to update inactive events. But maybe I missed some, could you > verify?
Thanks for the input. I will check it.
> >
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