linux-kernel - Re: [PATCH v2 0/3] perf: introduce perf based task analyzer

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Message-ID: <CAM9d7chLZVDg_-tnUh_qFYzchnpis-e7HYNDVM_OPjj_QXMeKQ@mail.gmail.com>
Date:   Wed, 7 Dec 2022 20:59:15 -0800
From:   Namhyung Kim <namhyung@...nel.org>
To:     Petar Gligoric <petar.gligor@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        Petar Gligoric <petar.gligoric@...de-schwarz.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
        Ian Rogers <irogers@...gle.com>
Subject: Re: [PATCH v2 0/3] perf: introduce perf based task analyzer

On Tue, Dec 6, 2022 at 2:21 PM Petar Gligoric <petar.gligor@...il.com> wrote:
>
> On Tue, Dec 06, 2022 at 10:32:35AM -0800, Namhyung Kim wrote:
> > Hello,
> >
> > Have you looked at 'perf sched timehist' ?
> > I think it has the common functionality and can be easily extended if there's
> > missing one.
> >
> > Thanks,
> > Namhyung
> >
>
> Thanks for the input! For this patchset we explicitly decided against
> extending "perf sched timehist" - after some pros and cons. Mainly we
> didn't want to break existing programs (which might parse the output of
> perf sched) and also the goal of the task-analyzer is a bit different.
> E.g what will follow as a follow-up patch, is to show IRQs visually
> pleasing intermixed with tasks to show potential sources of task
> latency. This will be offered as an option for the task-analyzer, but
> would be too much functionality for "perf sched timehist". This was the
> main reason why we decided against the extension.

Then you might want to add a new sub-command under perf sched.
But I guess we can just add a new option for the different output
format in the perf sched timehist.

Anyway, "perf script" is a generic tool not targeting specific events.
This functionality requires sched_switch (and more?) then we need
the record part to make sure the data has the events.  That's why
it's natural to have it in perf sched IMHO.

Thanks,
Namhyung