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SubjectRe: [PATCH 6/8] perf: Account freq events per cpu
On Thu, Aug 01, 2013 at 02:46:58PM +0200, Jiri Olsa wrote:
> On Tue, Jul 23, 2013 at 02:31:04AM +0200, Frederic Weisbecker wrote:
> > This is going to be used by the full dynticks subsystem
> > as a finer-grained information to know when to keep and
> > when to stop the tick.
> >
> > Original-patch-by: Peter Zijlstra <peterz@infradead.org>
> > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> > Cc: Jiri Olsa <jolsa@redhat.com>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Cc: Namhyung Kim <namhyung@kernel.org>
> > Cc: Ingo Molnar <mingo@kernel.org>
> > Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> > Cc: Stephane Eranian <eranian@google.com>
> > ---
> > kernel/events/core.c | 7 +++++++
> > 1 files changed, 7 insertions(+), 0 deletions(-)
> >
> > diff --git a/kernel/events/core.c b/kernel/events/core.c
> > index b40c3db..f9bd39b 100644
> > --- a/kernel/events/core.c
> > +++ b/kernel/events/core.c
> > @@ -141,6 +141,7 @@ enum event_type_t {
> > struct static_key_deferred perf_sched_events __read_mostly;
> > static DEFINE_PER_CPU(atomic_t, perf_cgroup_events);
> > static DEFINE_PER_CPU(atomic_t, perf_branch_stack_events);
> > +static DEFINE_PER_CPU(atomic_t, perf_freq_events);
> >
> > static atomic_t nr_mmap_events __read_mostly;
> > static atomic_t nr_comm_events __read_mostly;
> > @@ -3139,6 +3140,9 @@ static void unaccount_event_cpu(struct perf_event *event, int cpu)
> > }
> > if (is_cgroup_event(event))
> > atomic_dec(&per_cpu(perf_cgroup_events, cpu));
> > +
> > + if (event->attr.freq)
> > + atomic_dec(&per_cpu(perf_freq_events, cpu));
> > }
> >
> > static void unaccount_event(struct perf_event *event)
> > @@ -6473,6 +6477,9 @@ static void account_event_cpu(struct perf_event *event, int cpu)
> > }
> > if (is_cgroup_event(event))
> > atomic_inc(&per_cpu(perf_cgroup_events, cpu));
> > +
> > + if (event->attr.freq)
> > + atomic_inc(&per_cpu(perf_freq_events, cpu));
>
> cpu could be -1 in here.. getting:

Ho humm, right you are.

So we have:

static void account_event_cpu(struct perf_event *event, int cpu)
{
if (event->parent)
return;

if (has_branch_stack(event)) {
if (!(event->attach_state & PERF_ATTACH_TASK))
atomic_inc(&per_cpu(perf_branch_stack_events, cpu));
}
if (is_cgroup_event(event))
atomic_inc(&per_cpu(perf_cgroup_events, cpu));

if (event->attr.freq)
atomic_inc(&per_cpu(perf_freq_events, cpu));
}

Where the freq thing is new and shiney, but we already had the other
two. Of those, cgroup events must be per cpu so that should be good,
the branch_stack thing tests ATTACH_TASK, which should also be good, but
leaves me wonder wth they do for those that are attached to tasks.

But yes, the frequency thing is borken.


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