From: Andi Kleen <andi@firstfloor.org>
To: Christoph Lameter <cl@linux.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Mel Gorman <mel@csn.ul.ie>, Rob Mueller <robm@fastmail.fm>,
linux-kernel@vger.kernel.org, Bron Gondwana <brong@fastmail.fm>,
linux-mm <linux-mm@kvack.org>
Subject: Re: Default zone_reclaim_mode = 1 on NUMA kernel is bad forfile/email/web servers
Date: Thu, 30 Sep 2010 09:05:05 +0200 [thread overview]
Message-ID: <87aamzww2m.fsf@basil.nowhere.org> (raw)
In-Reply-To: <alpine.DEB.2.00.1009270828510.7000@router.home> (Christoph Lameter's message of "Mon, 27 Sep 2010 08:53:58 -0500 (CDT)")
Christoph Lameter <cl@linux.com> writes:
>
> 1. Fix the ACPI information to indicate lower memory access differences
> (was that info actually acurate?) so that zone reclaim defaults to off.
The reason the ACPI information is set this way is that the people who
tune the BIOS have some workload they care about which prefers zone
reclaim off and they know they can force this "faster setting" by faking
the distances.
Basically they're working around a Linux performance quirk.
Really I think some variant of Motohiro-san's patch is the right
solution: most problems with zone reclaim are related to IO
intensive workloads and it never made sense to have the unmapped
disk cache local on a system with reasonably small NUMA factor.
The only problem is on extremly big NUMA systems where remote nodes
are so slow that it's too slow even for read() and write().
I have been playing with the idea of adding a new "nearby interleave"
NUMA mode for this, but didn't have time to implement it so far.
For application I don't think we can ever solve it completely, this
probably always needs some kind of tuning. Currently the NUMA policy
APIs are not too good for this because they are too static, e.g. in some
cases "nearby" without fixed node affinity would also help here.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
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next prev parent reply other threads:[~2010-09-30 7:05 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1284349152.15254.1394658481@webmail.messagingengine.com>
2010-09-16 10:01 ` Default zone_reclaim_mode = 1 on NUMA kernel is bad for file/email/web servers KOSAKI Motohiro
2010-09-16 17:06 ` Christoph Lameter
2010-09-17 0:50 ` Robert Mueller
2010-09-17 6:01 ` Shaohua Li
2010-09-17 7:32 ` Robert Mueller
2010-09-17 13:56 ` Christoph Lameter
2010-09-17 14:09 ` Bron Gondwana
2010-09-17 14:22 ` Christoph Lameter
2010-09-17 23:01 ` Bron Gondwana
2010-09-20 9:34 ` Mel Gorman
2010-09-20 23:41 ` Default zone_reclaim_mode = 1 on NUMA kernel is bad forfile/email/web servers Rob Mueller
2010-09-21 9:04 ` Mel Gorman
2010-09-21 14:14 ` Christoph Lameter
2010-09-22 3:44 ` Rob Mueller
2010-09-27 2:01 ` KOSAKI Motohiro
2010-09-27 13:53 ` Christoph Lameter
2010-09-27 23:17 ` Robert Mueller
2010-09-28 12:35 ` Christoph Lameter
2010-09-28 12:42 ` Bron Gondwana
2010-09-28 12:49 ` Christoph Lameter
2010-09-30 7:05 ` Andi Kleen [this message]
2010-10-04 12:45 ` KOSAKI Motohiro
2010-10-04 13:07 ` Christoph Lameter
2010-10-05 5:32 ` KOSAKI Motohiro
2010-10-04 19:43 ` David Rientjes
2010-09-21 1:05 ` Default zone_reclaim_mode = 1 on NUMA kernel is bad for file/email/web servers KAMEZAWA Hiroyuki
2010-09-27 2:04 ` KOSAKI Motohiro
2010-09-27 2:06 ` KAMEZAWA Hiroyuki
2010-09-23 11:44 ` Balbir Singh
2010-09-30 8:38 ` Bron Gondwana
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