Re: [patch -mm 01/18] oom: filter tasks not sharing the same cpuset

From: David Rientjes <rientjes@google.com>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Rik van Riel <riel@redhat.com>, Nick Piggin <npiggin@suse.de>,
	Oleg Nesterov <oleg@redhat.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Balbir Singh <balbir@linux.vnet.ibm.com>,
	linux-mm@kvack.org
Subject: Re: [patch -mm 01/18] oom: filter tasks not sharing the same cpuset
Date: Tue, 8 Jun 2010 11:43:13 -0700 (PDT)	[thread overview]
Message-ID: <alpine.DEB.2.00.1006081141330.18848@chino.kir.corp.google.com> (raw)
In-Reply-To: <20100607084024.873B.A69D9226@jp.fujitsu.com>

On Tue, 8 Jun 2010, KOSAKI Motohiro wrote:

> I've put following historically remark in the description of the patch.
> 
> 
>     We applied the exactly same patch in 2005:
> 
>         : commit ef08e3b4981aebf2ba9bd7025ef7210e8eec07ce
>         : Author: Paul Jackson <pj@sgi.com>
>         : Date:   Tue Sep 6 15:18:13 2005 -0700
>         :
>         : [PATCH] cpusets: confine oom_killer to mem_exclusive cpuset
>         :
>         : Now the real motivation for this cpuset mem_exclusive patch series seems
>         : trivial.
>         :
>         : This patch keeps a task in or under one mem_exclusive cpuset from provoking an
>         : oom kill of a task under a non-overlapping mem_exclusive cpuset.  Since only
>         : interrupt and GFP_ATOMIC allocations are allowed to escape mem_exclusive
>         : containment, there is little to gain from oom killing a task under a
>         : non-overlapping mem_exclusive cpuset, as almost all kernel and user memory
>         : allocation must come from disjoint memory nodes.
>         :
>         : This patch enables configuring a system so that a runaway job under one
>         : mem_exclusive cpuset cannot cause the killing of a job in another such cpuset
>         : that might be using very high compute and memory resources for a prolonged
>         : time.
> 
>     And we changed it to current logic in 2006
> 
>         : commit 7887a3da753e1ba8244556cc9a2b38c815bfe256
>         : Author: Nick Piggin <npiggin@suse.de>
>         : Date:   Mon Sep 25 23:31:29 2006 -0700
>         :
>         : [PATCH] oom: cpuset hint
>         :
>         : cpuset_excl_nodes_overlap does not always indicate that killing a task will
>         : not free any memory we for us.  For example, we may be asking for an
>         : allocation from _anywhere_ in the machine, or the task in question may be
>         : pinning memory that is outside its cpuset.  Fix this by just causing
>         : cpuset_excl_nodes_overlap to reduce the badness rather than disallow it.
> 
>     And we haven't get the explanation why this patch doesn't reintroduced
>     an old issue. 
> 
> I don't refuse a patch if it have multiple ack. But if you have any
> material or number, please show us soon.
> 

And this patch is acked by the 2006 patch's author, Nick Piggin.

There's obviously not going to be any "number" to show that this means 
anything, but we've run it internally for three years to prevent needless 
oom killing in other cpusets that don't have any indication that it will 
free memory that current needs.

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