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From: Minchan Kim <minchan.kim@gmail.com>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mel@csn.ul.ie>, Johannes Weiner <hannes@cmpxchg.org>,
	Wu Fengguang <fengguang.wu@intel.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Rik van Riel <riel@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	linux-mm@kvack.org, Christoph Lameter <cl@linux.com>
Subject: Re: [patch] mm: fix deferred congestion timeout if preferred zone is not allowed
Date: Wed, 19 Jan 2011 13:10:06 +0900	[thread overview]
Message-ID: <AANLkTikhkiw0dx_5aj3habTbhofN_=Ptz7J0eDa49eN9@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1101181751420.25382@chino.kir.corp.google.com>

On Wed, Jan 19, 2011 at 10:53 AM, David Rientjes <rientjes@google.com> wrote:
> On Wed, 19 Jan 2011, Minchan Kim wrote:
>
>> >
>> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> > --- a/mm/page_alloc.c
>> > +++ b/mm/page_alloc.c
>> > @@ -2034,6 +2034,18 @@ restart:
>> >         */
>> >        alloc_flags = gfp_to_alloc_flags(gfp_mask);
>> >
>> > +       /*
>> > +        * If preferred_zone cannot be allocated from in this context, find the
>> > +        * first allowable zone instead.
>> > +        */
>> > +       if ((alloc_flags & ALLOC_CPUSET) &&
>> > +           !cpuset_zone_allowed_softwall(preferred_zone, gfp_mask)) {
>> > +               first_zones_zonelist(zonelist, high_zoneidx,
>> > +                               &cpuset_current_mems_allowed, &preferred_zone);
>>
>> This patch is one we need. but I have a nitpick.
>> I am not familiar with CPUSET so I might be wrong.
>>
>> I think it could make side effect of statistics of ZVM on
>> buffered_rmqueue since you intercept and change preferred_zone.
>> It could make NUMA_HIT instead of NUMA_MISS.
>> Is it your intention?
>>
>
> It depends on the semantics of NUMA_MISS: if no local nodes are allowed by
> current's cpuset (a pretty poor cpuset config :), then it seems logical
> that all allocations would be a miss.

It does make sense to me but I delegate the decision to Christoph who is author.
And please write down this behavior change into changelog. :)
Thanks David.



-- 
Kind regards,
Minchan Kim

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  reply	other threads:[~2011-01-19  4:10 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-18  5:09 David Rientjes
2011-01-18  6:04 ` KOSAKI Motohiro
2011-01-18 10:29   ` Mel Gorman
2011-01-19 12:48     ` KOSAKI Motohiro
2011-01-18 10:15 ` Mel Gorman
2011-01-18 20:24   ` David Rientjes
2011-01-18 20:42     ` Mel Gorman
2011-01-19  1:51       ` David Rientjes
2011-01-19 13:01     ` KOSAKI Motohiro
2011-01-19 18:37       ` David Rientjes
2011-01-19 12:52   ` KOSAKI Motohiro
2011-01-19  0:43 ` Minchan Kim
2011-01-19  1:53   ` David Rientjes
2011-01-19  4:10     ` Minchan Kim [this message]
2011-01-19 19:59     ` Christoph Lameter
2011-01-19 20:06       ` Andi Kleen
2011-01-19 20:18         ` David Rientjes
2011-01-19 23:07           ` Christoph Lameter
2011-01-20  0:59           ` Minchan Kim
2011-01-23 22:30 ` [patch v2] " David Rientjes
2011-01-24 17:16   ` Rik van Riel

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