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

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Date:	Fri, 24 Aug 2012 17:32:21 +0400
From:	Andrey Wagin <avagin@...il.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	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)

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?

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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