linux-kernel - Re: [RFC][PATCH] oom_kill: avoid depends on total_vm and use real RSS/swap value for oom

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Message-ID: <4AE730C2.30401@gmail.com>
Date:	Tue, 27 Oct 2009 18:41:22 +0100
From:	Vedran Furač <vedran.furac@...il.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
CC:	Minchan Kim <minchan.kim@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	"hugh.dickins@...cali.co.uk" <hugh.dickins@...cali.co.uk>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	rientjes@...gle.com
Subject: Re: [RFC][PATCH] oom_kill: avoid depends on total_vm and use real
 RSS/swap value for oom_score (Re: Memory overcommit

KAMEZAWA Hiroyuki wrote:

> On Tue, 27 Oct 2009 15:55:26 +0900
> Minchan Kim <minchan.kim@...il.com> wrote:
> 
>>>> Hmm.
>>>> I wonder why we consider VM size for OOM kiling.
>>>> How about RSS size?
>>>>
>>> Maybe the current code assumes "Tons of swap have been generated, already" if
>>> oom-kill is invoked. Then, just using mm->anon_rss will not be correct.
>>>
>>> Hm, should we count # of swap entries reference from mm ?....
>> In Vedran case, he didn't use swap. So, Only considering vm is the problem.
>> I think it would be better to consider both RSS + # of swap entries as
>> Kosaki mentioned.
>>
> Then, maybe this kind of patch is necessary.
> This is on 2.6.31...then I may have to rebase this to mmotom.
> Added more CCs.
> 
> Vedran, I'm glad if you can test this patch.

Thanks for the patch! I'll test it during this week a report after that.

> Instead of total_vm, we should use anon/file/swap usage of a process, I think.
> This patch adds mm->swap_usage and calculate oom_score based on
>   anon_rss + file_rss + swap_usage.

Isn't file_rss shared between processes? Sorry, I'm newbie. :)

% pmap $(pidof test)
29049:   ./test
0000000000400000      4K r-x--  /home/vedranf/dev/tmp/test
0000000000600000      4K rw---  /home/vedranf/dev/tmp/test
00002ba362a80000    116K r-x--  /lib/ld-2.10.1.so
00002ba362a9d000     12K rw---    [ anon ]
00002ba362c9c000      4K r----  /lib/ld-2.10.1.so
00002ba362c9d000      4K rw---  /lib/ld-2.10.1.so
00002ba362c9e000   1320K r-x--  /lib/libc-2.10.1.so
00002ba362de8000   2044K -----  /lib/libc-2.10.1.so
00002ba362fe7000     16K r----  /lib/libc-2.10.1.so
00002ba362feb000      4K rw---  /lib/libc-2.10.1.so
00002ba362fec000 1024028K rw---    [ anon ] // <-- This
00007ffff4618000     84K rw---    [ stack ]
00007ffff47b7000      4K r-x--    [ anon ]
ffffffffff600000      4K r-x--    [ anon ]
 total          1027648K

I would just look at anon if that's OK (or possible).

> Considering usual applications, this will be much better information than
> total_vm.

Agreed.

> score   PID     name
> 4033	3176	gnome-panel
> 4077	3113	xinit
> 4526	3190	python
> 4820	3161	gnome-settings-
> 4989	3289	gnome-terminal
> 7105	3271	tomboy
> 8427	3177	nautilus
> 17549	3140	gnome-session
> 128501	3299	bash
> 256106	3383	mmap
> 
> This order is not bad, I think.

Yes, this looks much better now.  Bash is only having somewhat strangely
high score.

Regards,

Vedran


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