linux-kernel - Re: [PATCH 13/18] perf metric: Add events for the current group

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Date:   Wed, 15 Jul 2020 15:14:37 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Michael Petlan <mpetlan@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        John Garry <john.garry@...wei.com>,
        "Paul A. Clarke" <pc@...ibm.com>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 13/18] perf metric: Add events for the current group

On Wed, Jul 15, 2020 at 2:19 PM Jiri Olsa <jolsa@...hat.com> wrote:
>
> On Wed, Jul 15, 2020 at 10:00:09AM -0700, Ian Rogers wrote:
> > On Sun, Jul 12, 2020 at 6:27 AM Jiri Olsa <jolsa@...nel.org> wrote:
> > >
> > > There's no need to iterate the whole list of groups,
> > > when adding new events. The currently created group
> > > is the one we want to add.
> > >
> > > Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> > > ---
> > >  tools/perf/util/metricgroup.c | 22 ++++++++++++----------
> > >  1 file changed, 12 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> > > index 8cbcc5e05fef..66f25362702d 100644
> > > --- a/tools/perf/util/metricgroup.c
> > > +++ b/tools/perf/util/metricgroup.c
> > > @@ -811,17 +811,19 @@ static int metricgroup__add_metric(const char *metric, bool metric_no_group,
> >
> > Could we add a function comment to describe the arguments here?
>
> ok
>
> > Currently events is an empty list out argument that is built up by
> > this code, now it will be incrementally updated. Except I don't think
> > I'm capturing the current state correctly, it is confusing that there
> > is the loop in the current code. It looks like events will be added
> > multiple times redundantly.
>
> oops, I meant to add the example of broken processing in here,
> but forgot.. will update
>
> >
> > >         if (ret)
> > >                 return ret;
> > >
> > > -       list_for_each_entry(eg, group_list, nd) {
> > > -               if (events->len > 0)
> > > -                       strbuf_addf(events, ",");
> > > +       if (events->len > 0)
> > > +               strbuf_addf(events, ",");
> > >
> > > -               if (eg->has_constraint) {
> > > -                       metricgroup__add_metric_non_group(events,
> > > -                                                         &eg->pctx);
> > > -               } else {
> > > -                       metricgroup__add_metric_weak_group(events,
> > > -                                                          &eg->pctx);
> > > -               }
> > > +       /*
> > > +        * Even if we add multiple groups through the runtime
> > > +        * param, they share same events.
> > > +        */
> >
> > I'm not clear what runtime param is here. Is it the \? arch runtime parameter?
>
> yes, that's that ppc quirk.. adding extra same metrics based
> on that runtime param.. for some reason ;-)

Do they share the same event? I thought the "?" was substituted in a
loop for a value 0...arch_runtime_value and so you got an event for
each of those values.

Thanks,
Ian

> thanks,
> jirka
>