Re: [PATCH 4/5] perf tools: Allow to ignore missing pid

From	Arnaldo Carvalho de Melo <acme@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 4/5] perf tools: Allow to ignore missing pid
Date	2016-12-12 20:40 +0100
Message-ID	<sNEC6-8kr-13@gated-at.bofh.it> (permalink)
References	(1 earlier) <sNwbw-3aN-23@gated-at.bofh.it> <sNzVL-5vw-7@gated-at.bofh.it> <sNAf8-5C8-23@gated-at.bofh.it> <sNAI9-61i-35@gated-at.bofh.it> <sNARQ-64o-15@gated-at.bofh.it>
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Em Mon, Dec 12, 2016 at 04:38:44PM +0100, Jiri Olsa escreveu:
> On Mon, Dec 12, 2016 at 12:21:49PM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Mon, Dec 12, 2016 at 03:53:12PM +0100, Jiri Olsa escreveu:
> > > On Mon, Dec 12, 2016 at 11:32:09AM -0300, Arnaldo Carvalho de Melo wrote:
> > > > Em Mon, Dec 12, 2016 at 11:35:42AM +0100, Jiri Olsa escreveu:
> > > > > Adding perf_evsel::ignore_missing_cpu_thread bool.
> > > > > 
> > > > > When set true, it allows perf to ignore error of missing
> > > > > pid of perf event syscall.
> > > > > 
> > > > > We remove missing thread id from the thread_map, so the
> > > > > rest of the processing like ioctl and mmap won't get
> > > > > disturbed with -1 fd
> > > > 
> > > > What was the test performed? I tried it here the following while doing
> > > > a 'make -j4 allmodconfig' in the background, i.e. tons of threads coming
> > > > and going, and I sometimes get:
> > > > 
> > > > [root@jouet ~]# perf record -u acme 
> > > > Error:
> > > > The sys_perf_event_open() syscall returned with 3 (No such process) for
> > > > event (cycles:ppp).
> > > > /bin/dmesg may provide additional information.
> > > > No CONFIG_PERF_EVENTS=y kernel support configured?
> > > 
> > > I dont think it's fast enough (start/stop) to hit the race, I've got best
> > > results with having on background this:
> > > 
> > >   while :; do /usr/bin/true; done
> > 
> > Ok, but the focus of my message wasn't on generating threads, was in
> > having the above happen with your patch applied.
> 
> hum, actualy the patch 5 enables that for -u option.. this patch just adds the logic

Sure, I noticed that, and the above is with your patches, all of them,
that is why I asked about this behaviour, how you tested it, etc.

- Arnaldo

Thread

[PATCH 0/5] perf record: Allow to ignore missing pid Jiri Olsa <jolsa@kernel.org> - 2016-12-12 11:40 +0100
  [PATCH 4/5] perf tools: Allow to ignore missing pid Jiri Olsa <jolsa@kernel.org> - 2016-12-12 11:40 +0100
    Re: [PATCH 4/5] perf tools: Allow to ignore missing pid Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-12 15:40 +0100
    Re: [PATCH 4/5] perf tools: Allow to ignore missing pid Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-12 15:40 +0100
      Re: [PATCH 4/5] perf tools: Allow to ignore missing pid Jiri Olsa <jolsa@redhat.com> - 2016-12-12 16:00 +0100
        Re: [PATCH 4/5] perf tools: Allow to ignore missing pid Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-12 16:30 +0100
          Re: [PATCH 4/5] perf tools: Allow to ignore missing pid Jiri Olsa <jolsa@redhat.com> - 2016-12-12 16:40 +0100
            Re: [PATCH 4/5] perf tools: Allow to ignore missing pid Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-12-12 20:40 +0100
    Re: [PATCH 4/5] perf tools: Allow to ignore missing pid Namhyung Kim <namhyung@kernel.org> - 2016-12-12 18:00 +0100
      [PATCHv2 4/5] perf tools: Allow to ignore missing pid Jiri Olsa <jolsa@redhat.com> - 2016-12-13 08:50 +0100
        [tip:perf/urgent] perf evsel: Allow to ignore missing pid tip-bot for Jiri Olsa <tipbot@zytor.com> - 2016-12-20 20:30 +0100

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