From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Olsa <jolsa@redhat.com>
Cc: linux-kernel@vger.kernel.org,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
Ingo Molnar <mingo@elte.hu>, Paul Mackerras <paulus@samba.org>,
Corey Ashford <cjashfor@linux.vnet.ibm.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Namhyung Kim <namhyung@kernel.org>,
Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH 1/2] perf: Enable wakeup_events logic for all events
Date: Thu, 30 May 2013 13:02:39 +0200 [thread overview]
Message-ID: <20130530110239.GN12193@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1369907587-8963-2-git-send-email-jolsa@redhat.com>
On Thu, May 30, 2013 at 11:53:06AM +0200, Jiri Olsa wrote:
> Currently the perf_events_attr::wakeup_events logic is
> checked only for regular samples.
>
> If we have an event that produce only auxiliary events
> (MMAP|COMM|EXIT|FORK), the poll call does not follow
> the perf_events_attr wakeup_events setup and reports
> no data.
>
> Fixing this by moving the perf_events_attr::wakeup_events
> checking logic into the function and calling it from
> perf_output_end. This way any output event is checked
> properly.
>
So something like this came up before and ISTR doing a patch similar to
what you propose but ended up not going with it because... uhm...
I have vague memories about people (possibly me) wanting wake_events to
mean samples. Like get me a wakeup every 20 samples. With your patch the
side-band events now also count towards 'events'.
I think the most common use of wake_events is people setting it to 1 and
have perf generate a SIGfoo for every sample so they can do magic in
their userspace signal handler. This is popular for interpreters.
It would be unfortunate to get SIGfoos for side-band chatter.
Makes sense?
next prev parent reply other threads:[~2013-05-30 11:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-30 9:53 [PATCH 0/2] perf: Fix wakeup_events logic Jiri Olsa
2013-05-30 9:53 ` [PATCH 1/2] perf: Enable wakeup_events logic for all events Jiri Olsa
2013-05-30 11:02 ` Peter Zijlstra [this message]
2013-05-30 11:45 ` Jiri Olsa
2013-05-30 11:51 ` Arnaldo Carvalho de Melo
2013-05-30 11:56 ` Jiri Olsa
2013-05-30 9:53 ` [PATCH 2/2] perf tests: Add auxiliary events poll automated test Jiri Olsa
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