linux-kernel - Re: [PATCH 1/2] perf: Enable wakeup

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Message-ID: <20130530115627.GC1099@krava.brq.redhat.com>
Date:	Thu, 30 May 2013 13:56:27 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Paul Mackerras <paulus@...ba.org>,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 1/2] perf: Enable wakeup_events logic for all events

On Thu, May 30, 2013 at 02:51:13PM +0300, Arnaldo Carvalho de Melo wrote:
> Em Thu, May 30, 2013 at 01:02:39PM +0200, Peter Zijlstra escreveu:
> > 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.
> 
> > 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 it was me, and the test case is tools/perf/pythoh/twatch.py,
> that just wants those side band events, the "fix" was:
> 
> commit cfeb1d90a1b1db96383b48888cb7a5f10ca12e12
> Author: Arnaldo Carvalho de Melo <acme@...hat.com>
> Date:   Mon Jan 30 14:43:21 2012 -0200
> 
>     perf python: Use attr.watermark in twatch.py
>     
>     We want to be woken up for every PERF_RECORD_ event,
> attr.wakeup_events is only for PERF_RECORD_SAMPLE, so also use
> attr.watermark = 1 to fix that.

ah right, using wattermark=1.. ok ;-)

thanks,
jirka
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