From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id EA22D6B0047 for ; Sun, 26 Sep 2010 22:01:48 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o8R21j8b009932 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Mon, 27 Sep 2010 11:01:45 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 8DBB745DE52 for ; Mon, 27 Sep 2010 11:01:44 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id E348F45DE53 for ; Mon, 27 Sep 2010 11:01:43 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id B34111DB8043 for ; Mon, 27 Sep 2010 11:01:42 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.249.87.106]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id CCE331DB8037 for ; Mon, 27 Sep 2010 11:01:41 +0900 (JST) From: KOSAKI Motohiro Subject: Re: Default zone_reclaim_mode = 1 on NUMA kernel is bad forfile/email/web servers In-Reply-To: <20100921090407.GA11439@csn.ul.ie> References: <52C8765522A740A4A5C027E8FDFFDFE3@jem> <20100921090407.GA11439@csn.ul.ie> Message-Id: <20100927110049.6B31.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Mon, 27 Sep 2010 11:01:41 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: kosaki.motohiro@jp.fujitsu.com, Rob Mueller , linux-kernel@vger.kernel.org, Bron Gondwana , linux-mm , Christoph Lameter List-ID: Hi > No doubt this is true. The only real difference is that there are more NUMA > machines running mail/web/file servers now than there might have been in the > past. The default made sense once upon a time. Personally I wouldn't mind > the default changing but my preference would be that distribution packages > installing on NUMA machines would prompt if the default should be changed if it > is likely to be of benefit for that package (e.g. the mail, file and web ones). At first impression, I thought this is cute idea. But, after while thinking, I've found some weak point. The problem is, too many package need to disable zone_reclaim_mode. zone_reclaim doesn't works fine if an application need large working set rather than local node size. It mean major desktop applications (e.g. OpenOffice.org, Firefox, GIMP) need to disable zone_reclaim. It mean even though basic package installation require zone_reclaim disabling. Then, this mechanism doesn't works practically. Even though the user hope to use the machine for hpc, disable zone_reclaim will be turn on anyway. Probably, opposite switch (default is zone_reclaim=0, and installation MPI library change to zone_reclaim=1) might works. but I can guess why you don't propose this one. Hmm.... -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org