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From: Michel Lespinasse <walken@google.com>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux.com>,
	akpm@linux-foundation.org, npiggin@kernel.dk,
	Pekka Enberg <penberg@cs.helsinki.fi>,
	David Rientjes <rientjes@google.com>,
	linux-mm@kvack.org, Andi Kleen <andi@firstfloor.org>
Subject: Re: shrinkers: Add node to indicate where to target shrinking
Date: Sun, 14 Nov 2010 03:05:36 -0800	[thread overview]
Message-ID: <AANLkTi=xPYe6KVVNM7y+tnDAWcVOMb_6jKo5Hq8QNSC8@mail.gmail.com> (raw)
In-Reply-To: <20101114161059.BED5.A69D9226@jp.fujitsu.com>

On Sat, Nov 13, 2010 at 11:10 PM, KOSAKI Motohiro
<kosaki.motohiro@jp.fujitsu.com> wrote:
>> On Thu, Oct 21, 2010 at 11:00 AM, Christoph Lameter <cl@linux.com> wrote:
>> > @@ -218,6 +218,7 @@ unsigned long shrink_slab(unsigned long
>> >                unsigned long total_scan;
>> >                unsigned long max_pass;
>> >
>> > +               shrinker->node = node;
>> >                max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask);
>> >                delta = (4 * scanned) / shrinker->seeks;
>> >                delta *= max_pass;
>>
>> Apologies for coming late to the party, but I have to ask - is there
>> anything protecting shrinker->node from concurrent modification if
>> several threads are trying to reclaim memory at once ?
>
> shrinker_rwsem? :)

Doesn't work - it protects shrink_slab() from concurrent modifications
of the shrinker_list in register_shrinker() or unregister_shrinker(),
but several shirnk_slab() calls can still execute in parallel since
they only grab shrinker_rwsem in shared (read) mode.

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.

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  reply	other threads:[~2010-11-14 11:05 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-21 17:59 vmscan: Do not run shrinkers for zones other than ZONE_NORMAL Christoph Lameter
2010-10-21 18:00 ` shrinkers: Add node to indicate where to target shrinking Christoph Lameter
2010-10-21 18:12   ` Andi Kleen
2010-10-21 20:57   ` David Rientjes
2010-10-21 21:07     ` Christoph Lameter
2010-10-22 13:27     ` Andi Kleen
2010-10-21 23:58   ` Nick Piggin
2010-10-22 12:12     ` Andi Kleen
2010-10-22 15:55     ` Christoph Hellwig
2010-10-22 16:32       ` Christoph Lameter
2010-10-24  1:42         ` Nick Piggin
2010-10-25  0:57           ` KOSAKI Motohiro
2010-10-25 14:59           ` Christoph Lameter
2010-11-09  4:03             ` Nick Piggin
2010-10-22 16:46       ` Andi Kleen
2010-10-24  1:31       ` Nick Piggin
2010-11-14  2:26   ` Michel Lespinasse
2010-11-14  7:10     ` KOSAKI Motohiro
2010-11-14 11:05       ` Michel Lespinasse [this message]
2010-11-15  0:29         ` KOSAKI Motohiro
2010-10-21 18:13 ` vmscan: Do not run shrinkers for zones other than ZONE_NORMAL Andi Kleen
2010-10-21 18:22   ` Christoph Lameter
2010-10-21 18:27   ` Christoph Lameter
2010-10-21 18:33     ` Andi Kleen
2010-10-21 20:48     ` David Rientjes
2010-10-21 20:54       ` Christoph Lameter
2010-10-21 19:40 ` Andrew Morton
2010-10-21 20:03   ` Christoph Lameter
2010-10-21 20:14     ` Andrew Morton
2010-10-21 20:28       ` Christoph Lameter
2010-10-21 20:36         ` Andrew Morton
2010-10-21 20:49           ` Christoph Lameter
2010-10-21 20:59             ` Andrew Morton
2010-10-21 21:13               ` Christoph Lameter
2010-10-21 21:21                 ` Andrew Morton
2010-10-21 23:04                   ` Christoph Lameter
2010-10-21 23:56 ` Nick Piggin
2010-10-22  1:37 ` KOSAKI Motohiro
2010-10-22 14:06   ` Christoph Lameter
2010-10-24  1:37     ` Nick Piggin
2010-10-25  1:22     ` KOSAKI Motohiro
2010-10-25 15:07       ` Christoph Lameter
2010-10-26  2:52         ` KOSAKI Motohiro
2010-10-26 12:42           ` KOSAKI Motohiro
2010-10-26 13:10           ` Christoph Lameter

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