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

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Date:	Wed, 28 Oct 2009 09:13:21 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	vedran.furac@...il.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

On Tue, 27 Oct 2009 18:41:22 +0100
Vedran Furač <vedran.furac@...il.com> wrote:

> 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. :)
> 
It's shared. But in typical case, file_rss will very small at OOM.


> % 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.
> 
It gets half score of mmap....If mmap goes, bash's score will goes down
dramatically. I'll read other's comments and tweak this patch more.

Thanks,
-Kame



> Regards,
> 
> Vedran
> 
> 
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