| Date | Thu, 14 Nov 2019 11:43:40 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 10/10] perf/cgroup: Do not switch system-wide events in cgroup switch |
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On Wed, Nov 13, 2019 at 04:30:42PM -0800, Ian Rogers wrote: > From: Kan Liang <kan.liang@linux.intel.com> > > When counting system-wide events and cgroup events simultaneously, the > system-wide events are always scheduled out then back in during cgroup > switches, bringing extra overhead and possibly missing events. Switching > out system wide flexible events may be necessary if the scheduled in > task's cgroups have pinned events that need to be scheduled in at a higher > priority than the system wide flexible events.
I'm thinking this patch is actively broken. groups->index 'group' wide and therefore across cpu/cgroup boundaries.
There is no !cgroup to cgroup hierarchy as this patch seems to assume, specifically look at how the merge sort in visit_groups_merge() allows cgroup events to be picked before !cgroup events.
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