Messages in this thread | | | From | Song Liu <> | Subject | Re: [PATCH v3] perf/core: Set event shadow time for inactive events too | Date | Sat, 18 Dec 2021 09:09:05 +0000 |
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> On Dec 17, 2021, at 8:35 AM, Peter Zijlstra <peterz@infradead.org> wrote: > > On Fri, Dec 10, 2021 at 11:33:41AM +0100, Peter Zijlstra wrote: > >> I'm thinking this is a cgroup specific thing. Normally the shadow_time >> thing is simply a relative displacement between event-time and the >> global clock. That displacement never changes, except when you do >> IOC_DISABLE/IOC_ENABLE. >> >> However, for cgroup things are different, since the cgroup events aren't >> unconditionally runnable, that is, the enabled time should only count >> when the cgroup is active, right? >> >> So perhaps perf_event_read_local() should use a cgroup clock instead of >> perf_clock() for cgroup events. >> >> Let me think about that some more... > > How's this then? Song, could you also please test and or better explain > the problem f79256532682 pretends to cure? Because the below is > reverting that, I *really* hate having to touch the events we're not > scheduling.
Unfortunately, this change bring the bug back. For time_enabled in rdpmc case to work properly, we have to touch all the enabled but not running events, right?
Thanks, Song
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