Messages in this thread | | | Date | Wed, 13 Oct 2021 18:26:33 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH v10 2/5] perf: Add a counter for number of user access events in context |
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On Tue, Sep 14, 2021 at 03:47:57PM -0500, Rob Herring wrote: > For controlling user space counter access, we need to know if any event > in a context (currently scheduled or not) is using user space counters. > Walking the context's list of events would be slow, so add a counter > to track this. > > Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Mark.
> --- > v10: > - Re-added. > - Maintain the count in the perf core > v9: > - Dropped > v8: > - new patch > --- > include/linux/perf_event.h | 1 + > kernel/events/core.c | 4 ++++ > 2 files changed, 5 insertions(+) > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index 12debf008d39..4f82a4d47139 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -821,6 +821,7 @@ struct perf_event_context { > > int nr_events; > int nr_active; > + int nr_user; > int is_active; > int nr_stat; > int nr_freq; > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 744e8726c5b2..01290d150da3 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -1808,6 +1808,8 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx) > > list_add_rcu(&event->event_entry, &ctx->event_list); > ctx->nr_events++; > + if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT) > + ctx->nr_user++; > if (event->attr.inherit_stat) > ctx->nr_stat++; > > @@ -1999,6 +2001,8 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) > event->attach_state &= ~PERF_ATTACH_CONTEXT; > > ctx->nr_events--; > + if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT) > + ctx->nr_user--; > if (event->attr.inherit_stat) > ctx->nr_stat--; > > -- > 2.30.2 >
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