Messages in this thread | | | Subject | Re: [PATCH 1/3] perf tools: Record total sampling time | From | Namhyung Kim <> | Date | Tue, 03 Dec 2013 00:05:49 +0900 |
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Hi Ingo,
2013-12-02 (월), 13:45 +0100, Ingo Molnar: > * Namhyung Kim <namhyung@kernel.org> wrote: > > > From: Namhyung Kim <namhyung.kim@lge.com> > > > > It's sometimes useful to see total sampling or elapsed time with > > normal performance result. To do that, record first and last sample > > time for each evsel and to display it in the header (--stdio only for > > now). > > > > $ perf record -a sleep 1 > > $ perf report --stdio > > ... > > # Samples: 4K of event 'cycles' > > # Event count (approx.): 4087481688 > > # Total sampling time : 1.001260 (sec) > > Btw., would it make sense to output it using the 'perf stat' print-out > machinery? > > If the 'count' of every event sampled is saved in the perf.data, > including elapsed time, at the beginning and at the end, then all > information is there to output things in perf stat style.
Yeah, it'd be great if we can share same code in the end.
> > ( It might even make sense to save two more timestamps: rusage stime > and utime - that way the output could be made /usr/bin/time-alike. )
Hmm.. I think I can do it by adding time info according to a cpumode in a sample.
> > Also I think there is some related existing functionality, I think > Stephane added a way to essentially do non-sampling 'perf stat' via > perf record - but the details escape me, I think it was related to the > -n option?
I have no idea about the perf record -n/--no-samples option. It looks like something related to task stat?
commit 649c48a9e7fafcc72bfcc99471d9dea98d789d59 Author: Peter Zijlstra <a.p.zijlstra@chello.nl> Date: Wed Jun 24 21:12:48 2009 +0200
perf-report: Add modes for inherited stats and no-samples
Now that we can collect per task statistics, add modes that make use of that facility.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
But everytime I tried to use it, perf report always complained about the file has no samples.. :-/
> > So what we want here is in essence a sampling mode that can record and > report all the absolute counts as well.
Agreed.
Thanks, Namhyung
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