From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 27 Feb 2008 14:00:42 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC][PATCH] page reclaim throttle take2 Message-Id: <20080227140042.66abb805.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20080227133850.4249.KOSAKI.MOTOHIRO@jp.fujitsu.com> References: <20080227131939.4244.KOSAKI.MOTOHIRO@jp.fujitsu.com> <47C4E6CD.6090401@linux.vnet.ibm.com> <20080227133850.4249.KOSAKI.MOTOHIRO@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KOSAKI Motohiro Cc: balbir@linux.vnet.ibm.com, Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Rik van Riel , Lee Schermerhorn , Nick Piggin List-ID: On Wed, 27 Feb 2008 13:45:18 +0900 KOSAKI Motohiro wrote: > Hi > > > One more thing, I would request you to add default heuristics (number of > > reclaimers), based on the number of cpus in the system. Letting people tuning it > > is fine, but defaults should be related to number of cpus, nodes and zones on > > the system. Zones can be reaped in parallel per node and cpus allow threads to > > run in parallel. So please use that to come up with good defaults, instead of a > > number like "3". > > I don't think so. > all modern many cpu machine stand on NUMA. > it mean following, > - if cpu increases, then zone increases, too. > > if default value increase by #cpus, lock contension dramatically increase > on large numa. > > Have I overlooked anything? > > How about adding something like.. == CONFIG_SIMULTANEOUS_PAGE_RECLAIMERS int default 3 depends on DEBUG help This value determines the number of threads which can do page reclaim in a zone simultaneously. If this is too big, performance under heavy memory pressure will decrease. If unsure, use default. == Then, you can get performance reports from people interested in this feature in test cycle. Thanks, -Kame -- 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