Messages in this thread | | | Date | Sun, 5 Dec 2021 15:15:58 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2] perf/core: Set event shadow time for inactive events too |
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On Tue, Nov 30, 2021 at 08:58:07PM -0800, Namhyung Kim wrote: > From: Namhyung Kim <namhyung@google.com> > > While f79256532682 ("perf/core: fix userpage->time_enabled of inactive > events") fixed this problem for user rdpmc usage, bperf (perf stat > with BPF) still has the same problem that accessing inactive perf > events from BPF using bpf_perf_event_read_value(). > > +static inline void group_update_event_time(struct perf_event *group_event) > { > + struct perf_event *event; > + struct perf_event_context *ctx = group_event->ctx;
:-( surely you're aware of the reverse xmas tree thing by now?
> > + perf_event_update_time(group_event); > + perf_set_shadow_time(group_event, ctx); > > + for_each_sibling_event(event, group_event) { > + perf_event_update_time(event); > + perf_set_shadow_time(event, ctx); > + } > > + if (likely(!atomic_read(&group_event->mmap_count))) > return; > > + perf_event_update_userpage(group_event); > + > for_each_sibling_event(event, group_event) > + perf_event_update_userpage(event);
How does it make sense to chase those pointers twice?
> }
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