linux-kernel - Re: [PATCH] oom_kill: use rss value instead of vm size for badness

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Date:	Fri, 4 Dec 2009 09:44:37 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Andrea Arcangeli <aarcange@...hat.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	vedran.furac@...il.com
Subject: Re: [PATCH] oom_kill: use rss value instead of vm size for badness

On Thu, 3 Dec 2009 15:25:05 -0800 (PST)
David Rientjes <rientjes@...gle.com> wrote:

> If Andrew pushes the patch to change the baseline to rss 
> (oom_kill-use-rss-instead-of-vm-size-for-badness.patch) to Linus, I'll 
> strongly nack it because you totally lack the ability to identify memory 
> leakers as defined by userspace which should be the prime target for the 
> oom killer.  You have not addressed that problem, you've merely talked 
> around it, and yet the patch unbelievably still sits in -mm.
>
It's still cook-time about oom-kill patches and I'll ask Andrew not to send
it when he asks in mm-merge plan. At least, per-mm swap counter and lowmem-rss
counter is necessary. I'll rewrite fork-bomb detector, too.

Repeatedly saying, calculating badness from vm_size _only_ is bad.
I'm not sure how google's magical applications works, but in general,
vm_size doesn't means private memory usage i.e. how well oom-killer can free
pages.
And current oom-killer kills wrong process. Please share your idea to making
oom-killer better rather than just saying "don't do that".

Do you have good algorithm for detecting memory-leaking process in user land ?
I think I added some in my old set but it's not enough.
I'll add more statistics to mm_struct to do better work.

BTW, I hate oom_adj very much. It's nature of "shift" is hard to understand.
I wonder why static oom priority or oom_threshold was not implemented...

Thanks,
-Kame 

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