linux-kernel - Re: [PATCH] oom: add tracepoints for oom_score

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Date:	Thu, 08 Dec 2011 12:33:35 -0500
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	kamezawa.hiroyu@...fujitsu.com
CC:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	akpm@...ux-foundation.org, rientjes@...gle.com, dchinner@...hat.com
Subject: Re: [PATCH] oom: add tracepoints for oom_score_adj

On 12/7/2011 8:47 PM, KAMEZAWA Hiroyuki wrote:
> On Wed, 07 Dec 2011 11:52:02 -0500
> KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> wrote:
> 
>> On 12/6/2011 7:54 PM, KAMEZAWA Hiroyuki wrote:
>>> >From 28189e4622fd97324893a0b234183f64472a54d6 Mon Sep 17 00:00:00 2001
>>> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>>> Date: Wed, 7 Dec 2011 09:58:16 +0900
>>> Subject: [PATCH] oom: trace point for oom_score_adj
>>>
>>> oom_score_adj is set to prevent a task from being killed by OOM-Killer.
>>> Some daemons sets this value and their children inerit it sometimes.
>>> Because inheritance of oom_score_adj is done automatically, users
>>> can be confused at seeing the value and finds it's hard to debug.
>>>
>>> This patch adds trace point for oom_score_adj. This adds 3 trace
>>> points. at
>>> 	- update oom_score_adj
>>
>>
>>> 	- fork()
>>> 	- rename task->comm(typically, exec())
>>
>> I don't think they have oom specific thing. Can you please add generic fork and
>> task rename tracepoint instead?
>>
> I think it makes oom-targeted debug difficult.
> This tracehook using task->signal->oom_score_adj as filter.
> This reduces traces much and makes debugging easier.
>  
> If you need another trace point for other purpose, another trace point
> should be better. For generic purpose, oom_socre_adj filtering will not
> be necessary.

see Documentation/trace/event.txt 5. Event filgtering

Now, both ftrace and perf have good filter feature. Isn't this enough?




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