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

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Message-ID: <BANLkTinKm=m8zdPGN0Trpy4HtEFyxMYzPA@mail.gmail.com>
Date:	Tue, 24 May 2011 17:46:54 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.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

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.
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.  :(




-- 
Kind regards,
Minchan Kim
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