linux-kernel - Re: [PATCH v4] oom: add trace points for debugging.

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Date:	Thu, 15 Dec 2011 00:55:44 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v4] oom: add trace points for debugging.

On Tue, 13 Dec 2011, KAMEZAWA Hiroyuki wrote:

> Subject: [PATCH] tracepoint: add tracepoints for debugging oom_score_adj.
> 
> oom_score_adj is used for guarding processes from OOM-Killer. One of problem
> is that it's inherited at fork(). When a daemon set oom_score_adj and
> make children, it's hard to know where the value is set.
> 
> This patch adds some tracepoints useful for debugging. This patch adds
> 3 trace points.
>   - creating new task
>   - renaming a task (exec)
>   - set oom_score_adj
> 
> To debug, users need to enable some trace pointer. Maybe filtering is useful as
> 
> # EVENT=/sys/kernel/debug/tracing/events/task/
> # echo "oom_score_adj != 0" > $EVENT/task_newtask/filter
> # echo "oom_score_adj != 0" > $EVENT/task_rename/filter
> # echo 1 > $EVENT/enable
> # EVENT=/sys/kernel/debug/tracing/events/oom/
> # echo 1 > $EVENT/enable
> 
> output will be like this.
> # grep oom /sys/kernel/debug/tracing/trace
> bash-7699  [007] d..3  5140.744510: oom_score_adj_update: pid=7699 comm=bash oom_score_adj=-1000
> bash-7699  [007] ...1  5151.818022: task_newtask: pid=7729 comm=bash clone_flags=1200011 oom_score_adj=-1000
> ls-7729  [003] ...2  5151.818504: task_rename: pid=7729 oldcomm=bash newcomm=ls oom_score_adj=-1000
> bash-7699  [002] ...1  5175.701468: task_newtask: pid=7730 comm=bash clone_flags=1200011 oom_score_adj=-1000
> grep-7730  [007] ...2  5175.701993: task_rename: pid=7730 oldcomm=bash newcomm=grep oom_score_adj=-1000
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

Acked-by: David Rientjes <rientjes@...gle.com>

Thanks for being persistant with this!
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