linux-kernel - Re: [PATCH 4/5] oom: don't kill random process

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Message-ID: <4DDB711B.8010408@jp.fujitsu.com>
Date:	Tue, 24 May 2011 17:49:31 +0900
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	minchan.kim@...il.com
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, caiqian@...hat.com, rientjes@...gle.com,
	hughd@...gle.com, kamezawa.hiroyu@...fujitsu.com, oleg@...hat.com
Subject: Re: [PATCH 4/5] oom: don't kill random process

(2011/05/24 17:46), Minchan Kim wrote:
> On Tue, May 24, 2011 at 10:53 AM, KOSAKI Motohiro
> <kosaki.motohiro@...fujitsu.com> wrote:
>>>> +       /*
>>>> +        * chosen_point==1 may be a sign that root privilege bonus is too
>>>> large
>>>> +        * and we choose wrong task. Let's recalculate oom score without
>>>> the
>>>> +        * dubious bonus.
>>>> +        */
>>>> +       if (protect_root&&  (chosen_points == 1)) {
>>>> +               protect_root = 0;
>>>> +               goto retry;
>>>> +       }
>>>
>>> The idea is good to me.
>>> But once we meet it, should we give up protecting root privileged
>>> processes?
>>> How about decaying bonus point?
>>
>> After applying my patch, unprivileged process never get score-1. (note,
>> mapping
>> anon pages naturally makes to increase nr_ptes)
> 
> Hmm, If I understand your code correctly, unprivileged process can get
> a score 1 by 3% bonus.

3% bonus is for privileged process. :)


> So after all, we can get a chosen_point with 1.
> Why I get a chosen_point with 1 is as bonus is rather big, I think.
> So I would like to use small bonus than first iteration(ie, decay bonus).
> 
>>
>> Then, decaying don't make any accuracy. Am I missing something?
> 
> Maybe I miss something.  :(
> 
> 
> 
> 


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