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: <20091028092251.8ddd1b20.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Wed, 28 Oct 2009 09:22:51 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Andrea Arcangeli <aarcange@...hat.com>
Cc:	Minchan Kim <minchan.kim@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	vedran.furac@...il.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 13:38:10 +0100
Andrea Arcangeli <aarcange@...hat.com> wrote:

> On Tue, Oct 27, 2009 at 04:56:12PM +0900, Minchan Kim wrote:
> > Thanks for making the patch.
> > Let's hear other's opinion. :)
> 
> total_vm is nearly meaningless, especially on 64bit that reduces the
> mmap load on libs, I tried to change it to something "physical" (rss,
> didn't add swap too) some time ago too, not sure why I didn't manage
> to get it in. Trying again surely sounds good. Accounting swap isn't
> necessarily good, we may be killing a task that isn't accessing memory
> at all. So yes, we free swap but if the task is the "bloater" it's
> unlikely to be all in swap as it did all recent activity that lead to
> the oom. So I'm unsure if swap is good to account here, but surely I
> ack to replace virtual with rss. I would include the whole rss, as the
> file one may also be rendered unswappable if it is accessed in a loop
> refreshing the young bit all the time.
> 
I wonder I'll acccounting swap and export it via /proc/<pid>/??? file.
So, I'll divide this patch into 2 part as swap accounting/oom patch.

Considering amount of swap at oom isn't very bad, I think. But using the
same weight to rss and swap is not good, maybe.

Hmm, maybe
   anon_rss + file_rss/2 + swap_usage/4 + kosaki's time accounting change
can give us some better value. I'll consider what number is logical and
technically correct, again.

I'll prepare series of 2-4? patches.

Thanks,
-Kame


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