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From: Andrew Vagin <avagin@openvz.org>
To: linux-kernel@vger.kernel.org
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Paul Mackerras <paulus@samba.org>,
	Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
	avagin@openvz.org
Subject: [PATCH 0/4] trace: add ability to collect call chains of non-current task.
Date: Mon, 26 Sep 2011 19:55:31 +0400	[thread overview]
Message-ID: <1317052535-1765247-1-git-send-email-avagin@openvz.org> (raw)

Without these patches, an event may only save call chain of a current
task, but some events may require call chains of non-current task.

E.g. You may want to know where and how long a task is sleeping. A time
slice is known when the task wakes up.  We send event in this moment,
but a target task isn't "current".

Usually when the system begin stuttering, it often waits a lock or an
operation for a long time. For investigation such situation you probaly
send sysrq-t and analyze backtraces, but perf may do it more effectively.

A macto __perf_task() is set task for wich a call chain will be collected.

Now this functionality is suitable for sched_stat_sleep and sched_stat_iowait.

             reply	other threads:[~2011-09-26 15:55 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-26 15:55 Andrew Vagin [this message]
2011-09-26 15:55 ` [PATCH 1/4] perf: fix counter of ftrace events Andrew Vagin
2011-10-14 19:11   ` Arun Sharma
2011-09-26 15:55 ` [PATCH 2/4] trace: prepare to collect call chains of non-current task Andrew Vagin
2011-09-27 14:02   ` Peter Zijlstra
2011-10-14 19:12   ` Arun Sharma
2011-09-26 15:55 ` [PATCH 3/4] trace: add ability to collect call chain " Andrew Vagin
2011-09-27 14:05   ` Peter Zijlstra
2011-09-27 20:55     ` Frederic Weisbecker
2011-09-28 13:53       ` Andrew Vagin
2011-12-08  2:02       ` Arun Sharma
2011-12-09 11:07         ` Andrey Vagin
2011-12-14 20:14           ` Arun Sharma
2011-12-15 15:19             ` Andrew Vagin
2011-12-15 19:08               ` Arun Sharma
2011-12-16  0:15                 ` Arun Sharma
2011-09-26 15:55 ` [PATCH 4/4] events: sched_stat_template saves call chains of a target task Andrew Vagin

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