From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Andi Kleen <ak@linux.intel.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH] perf record: Fix wrong comm in system-wide mode with delay
Date: Mon, 30 Aug 2021 15:54:42 -0300 [thread overview]
Message-ID: <YS0pcjdivueJcdwd@kernel.org> (raw)
In-Reply-To: <CAP-5=fWLUBzsaVNvHpJBMcZY+Ms3gE7OF6i3toOBaW-rYpVFeg@mail.gmail.com>
Em Mon, Aug 30, 2021 at 10:33:16AM -0700, Ian Rogers escreveu:
> On Fri, Aug 27, 2021 at 4:32 PM Namhyung Kim <namhyung@kernel.org> wrote:
> > Stephane found that the name of the forked process in a system-wide
> > mode is wrong when --delay option is used. For example,
> >
> > # perf record -a --delay=1000 noploop 3
> >
> > The noploop process will run a busy loop for 3 second. And on an idle
> > machine it should show up at the top in the perf report. It works
> > well without the --delay option. But if I add the option, it showed
> > 'perf' not 'noploop'.
> >
> > # perf report -s comm -q | head -3
> > 52.94% perf
> > 16.65% swapper
> > 12.04% chrome
> >
> > It turned out that the dummy event didn't work at all and it missed
> > COMM and MMAP events for the noploop process (and others too). We
> > should enable the dummy event immediately in system-wide mode, as the
> > enable-on-exec would work only for task events.
> >
> > With this change,
> >
> > # perf report -s comm -q | head -3
> > 52.75% noploop
> > 17.03% swapper
> > 12.83% chrome
> >
> > Cc: Adrian Hunter <adrian.hunter@intel.com>
> > Reported-by: Stephane Eranian <eranian@google.com>
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
>
> Acked-by: Ian Rogers <irogers@google.com>
Thanks, applied.
- Arnaldo
prev parent reply other threads:[~2021-08-30 18:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-27 23:32 [PATCH] perf record: Fix wrong comm in system-wide mode with delay Namhyung Kim
2021-08-30 17:33 ` Ian Rogers
2021-08-30 18:54 ` Arnaldo Carvalho de Melo [this message]
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