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From: Dave Hansen <dave@linux.vnet.ibm.com>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Christoph Lameter <cl@linux.com>,
	David Rientjes <rientjes@google.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Chris McDermott <lcm@linux.vnet.ibm.com>
Subject: Re: [PATCH resend^2] mm: increase RECLAIM_DISTANCE to 30
Date: Mon, 11 Apr 2011 14:29:31 -0700	[thread overview]
Message-ID: <1302557371.7286.16607.camel@nimitz> (raw)
In-Reply-To: <20110411172004.0361.A69D9226@jp.fujitsu.com>

On Mon, 2011-04-11 at 17:19 +0900, KOSAKI Motohiro wrote:
> This patch raise zone_reclaim_mode threshold to 30. 30 don't have
> specific meaning. but 20 mean one-hop QPI/Hypertransport and such
> relatively cheap 2-4 socket machine are often used for tradiotional
> server as above. The intention is, their machine don't use
> zone_reclaim_mode.

I know specifically of pieces of x86 hardware that set the information
in the BIOS to '21' *specifically* so they'll get the zone_reclaim_mode
behavior which that implies.

They've done performance testing and run very large and scary benchmarks
to make sure that they _want_ this turned on.  What this means for them
is that they'll probably be de-optimized, at least on newer versions of
the kernel.

If you want to do this for particular systems, maybe _that_'s what we
should do.  Have a list of specific configurations that need the
defaults overridden either because they're buggy, or they have an
unusual hardware configuration not really reflected in the distance
table.

-- Dave

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  parent reply	other threads:[~2011-04-11 21:29 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-11  8:19 [PATCH resend^2] mm: increase RECLAIM_DISTANCE to 30 KOSAKI Motohiro
2011-04-11 21:19 ` Andrew Morton
2011-04-12  0:59   ` KOSAKI Motohiro
2011-04-11 21:29 ` Dave Hansen [this message]
2011-04-12  1:01   ` KOSAKI Motohiro
2011-04-12  2:27     ` Dave Hansen
2011-04-12  7:25       ` KOSAKI Motohiro
2011-05-24 20:07       ` Andrew Morton
2011-05-24 20:24         ` David Rientjes
2011-05-24 20:37         ` Dave Hansen
2011-04-13  0:22   ` David Rientjes
2011-04-13  0:49     ` Dave Hansen
2011-04-13  0:56       ` David Rientjes
2011-04-13  0:16 ` David Rientjes
2011-04-13  0:26   ` Rob Mueller

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