linux-kernel - Re: [RFC PATCH v2] perf evsel: Fallback to task-clock when not system wide

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Date:   Mon, 4 Dec 2023 14:55:09 -0800
From:   Namhyung Kim <namhyung@...nel.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Yang Jihong <yangjihong1@...wei.com>,
        Leo Yan <leo.yan@...aro.org>,
        Sandipan Das <sandipan.das@....com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ajay Kaher <akaher@...are.com>,
        Alexey Makhalov <amakhalov@...are.com>
Subject: Re: [RFC PATCH v2] perf evsel: Fallback to task-clock when not system wide

On Mon, Dec 4, 2023 at 8:02 AM Ian Rogers <irogers@...gle.com> wrote:
>
> On Mon, Nov 20, 2023 at 4:04 PM Ian Rogers <irogers@...gle.com> wrote:
> >
> > When the cycles event isn't available evsel will fallback to the
> > cpu-clock software event. task-clock is similar to cpu-clock but only
> > runs when the process is running. Falling back to cpu-clock when not
> > system wide leads to confusion, by falling back to task-clock it is
> > hoped the confusion is less.
> >
> > Pass the target to determine if task-clock is more appropriate. Update
> > a nearby comment and debug string for the change.
> >
> > ---
> > v2. Use target__has_cpu as suggested by Namhyung.
> > https://lpc.events/event/17/contributions/1556/
> >
> > Signed-off-by: Ian Rogers <irogers@...gle.com>

Acked-by: Namhyung Kim <namhyung@...nel.org>

Thanks,
Namhyung