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From: Christoph Lameter <cl@linux.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Nick Piggin <npiggin@kernel.dk>,
	akpm@linux-foundation.org, 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: Fri, 22 Oct 2010 11:32:37 -0500 (CDT)	[thread overview]
Message-ID: <alpine.DEB.2.00.1010221121550.22051@router.home> (raw)
In-Reply-To: <20101022155513.GA26790@infradead.org>

On Fri, 22 Oct 2010, Christoph Hellwig wrote:
>
> I think making shrinking decision per-zone is fine.  But do we need to
> duplicate all the lru lists and infrastructure per-zone for that instead
> of simply per-zone?   Even with per-node lists we can easily skip over
> items from the wrong zone.
>
> Given that we have up to 6 zones per node currently, and we would mostly
> use one with a few fallbacks that seems like a lot of overkill.

Zones can also cause asymmetry in reclaim if per zone reclaim is done.

Look at the following zone setup of a Dell R910:

grep "^Node" /proc/zoneinfo
Node 0, zone      DMA
Node 0, zone    DMA32
Node 0, zone   Normal
Node 1, zone   Normal
Node 2, zone   Normal
Node 3, zone   Normal

A reclaim that does per zone reclaim (but in reality reclaims all objects
in a node (or worse as most shrinkers do today in the whole system) will
put 3x the pressure on node 0.

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  reply	other threads:[~2010-10-22 16:32 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 [this message]
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
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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