From 26a031e136f4f8dc82c64df48cca0eb3b5d3eb4f Mon Sep 17 00:00:00 2001
From: Andrew Vagin <avagin@openvz.org>
Date: Tue, 7 Aug 2012 16:56:04 +0400
Subject: perf inject: Merge sched_stat_* and sched_switch events

You may want to know where and how long a task is sleeping. A callchain
may be found in sched_switch and a time slice in stat_iowait, so I add
handler in perf inject for merging this events.

My code saves sched_switch event for each process and when it meets
stat_iowait, it reports the sched_switch event, because this event
contains a correct callchain. By another words it replaces all
stat_iowait events on proper sched_switch events.

I use the next sequence of commands for testing:

  perf record -e sched:sched_stat_sleep -e sched:sched_switch \
	      -e sched:sched_process_exit -g -o ~/perf.data.raw \
	      ~/test-program
  perf inject -v -s -i ~/perf.data.raw -o ~/perf.data
  perf report --stdio -i ~/perf.data
   100.00%	foo  [kernel.kallsyms]  [k] __schedule
               	|
                --- __schedule
                    schedule
                   |
                   |--79.75%-- schedule_hrtimeout_range_clock
                   |          schedule_hrtimeout_range
                   |          poll_schedule_timeout
                   |          do_select
                   |          core_sys_select
                   |          sys_select
                   |          system_call_fastpath
                   |          __select
                   |          __libc_start_main
                   |
                    --20.25%-- do_nanosleep
                              hrtimer_nanosleep
                              sys_nanosleep
                              system_call_fastpath
                              __GI___libc_nanosleep
                              __libc_start_main

 And here is test-program.c:

 #include<unistd.h>
 #include<time.h>
 #include<sys/select.h>

 int main()
 {
	struct timespec ts1;
	struct timeval tv1;
	int i;
	long s;

	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);
	}
	return 1;
 }

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1344344165-369636-4-git-send-email-avagin@openvz.org
[ committer note: Made it use evsel->handler ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/Documentation/perf-inject.txt | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'tools/perf/Documentation/perf-inject.txt')

diff --git a/tools/perf/Documentation/perf-inject.txt b/tools/perf/Documentation/perf-inject.txt
index 673ef97..a00a342 100644
--- a/tools/perf/Documentation/perf-inject.txt
+++ b/tools/perf/Documentation/perf-inject.txt
@@ -35,6 +35,11 @@ OPTIONS
 -o::
 --output=::
 	Output file name. (default: stdout)
+-s::
+--sched-stat::
+	Merge sched_stat and sched_switch for getting events where and how long
+	tasks slept. sched_switch contains a callchain where a task slept and
+	sched_stat contains a timeslice how long a task slept.
 
 SEE ALSO
 --------
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