linux-kernel - Re: [PATCH 0/4] perf: Teach perf tool to profile sleep times (v2)

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Date:	Fri, 24 Aug 2012 14:59:47 -0300
From:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
To:	Andrey Wagin <avagin@...il.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH 0/4] perf: Teach perf tool to profile sleep times (v2)

Em Fri, Aug 24, 2012 at 05:32:21PM +0400, Andrey Wagin escreveu:
> Hello Arnaldo,
> 
> What do you think about this series?
> 
> It has been fixed according with your comments to the previous
> patches. Are you going to take it?

I've put them in a perf/sleep branch in my tree, waiting on Frédéric
that is reviewing it.

- Arnaldo
 
> 2012/8/7 Andrew Vagin <avagin@...nvz.org>:
> > This functionality helps to analize where a task sleeps or waits locks.
> > This feature can help to investigate a scalability problems.
> >
> > The main idea is that we can combine sched_switch and sched_stat_sleep events.
> > sched_switch contains a callchain, when a task starts sleeping.
> > sched_stat_sleep contains a time period for which a task slept.
> >
> > This series teaches "perf inject" to combine this events.
> >
> > All kernel related patches were committed committed in 3.6-rc1.
> >
> > Here is an example of a report:
> > $ cat ~/foo.c
> > ....
> >           for (i = 0; i <  10; i++) {
> >                   ts1.tv_sec = 0;
> >                   ts1.tv_nsec = 10000000;
> >                   nanosleep(&ts1, NULL);
> >
> >                   tv1.tv_sec = 0;
> >                   tv1.tv_usec = 40000;
> >                   select(0, NULL, NULL, NULL,&tv1);
> >           }
> > ...
> >
> > $ ./perf record -e sched:sched_stat_sleep -e sched:sched_switch \
> >                 -e sched:sched_process_exit -gP -o ~/perf.data.raw ~/foo
> > [ perf record: Woken up 1 times to write data ]
> > [ perf record: Captured and wrote 0.015 MB /root/perf.data.raw (~661 samples) ]
> > $ ./perf inject -v -s -i ~/perf.data.raw -o ~/perf.data
> > $ ./perf report -i ~/perf.data
> > # Samples: 40  of event 'sched:sched_switch'
> > # Event count (approx.): 1005527702
> > #
> > # Overhead  Command      Shared Object          Symbol
> > # ........  .......  .................  ..............
> > #
> >    100.00%      foo  [kernel.kallsyms]  [k] __schedule
> >                 |
> >                 --- __schedule
> >                     schedule
> >                    |
> >                    |--79.81%-- schedule_hrtimeout_range_clock
> >                    |          schedule_hrtimeout_range
> >                    |          poll_schedule_timeout
> >                    |          do_select
> >                    |          core_sys_select
> >                    |          sys_select
> >                    |          system_call_fastpath
> >                    |          __select
> >                    |          __libc_start_main
> >                    |
> >                     --20.19%-- do_nanosleep
> >                               hrtimer_nanosleep
> >                               sys_nanosleep
> >                               system_call_fastpath
> >                               __GI___libc_nanosleep
> >                               __libc_start_main
> >
> > Andrew Vagin (3):
> >   perf: teach "perf inject" to work with files
> >   perf: teach perf inject to merge sched_stat_* and sched_switch events
> >   perf: mark a dso if it's used
> >
> >  tools/perf/builtin-inject.c |  139 ++++++++++++++++++++++++++++++++++++++++---
> >  tools/perf/util/build-id.c  |    2 +-
> >  tools/perf/util/build-id.h  |    5 ++
> >  3 files changed, 137 insertions(+), 9 deletions(-)
> >
> > --
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