From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 07FB56B01F1 for ; Thu, 19 Aug 2010 06:23:19 -0400 (EDT) Date: Thu, 19 Aug 2010 11:20:55 +0100 From: Chris Webb Subject: Re: Over-eager swapping Message-ID: <20100819102055.GK2370@arachsys.com> References: <20100804032400.GA14141@localhost> <20100804095811.GC2326@arachsys.com> <20100804114933.GA13527@localhost> <20100804120430.GB23551@arachsys.com> <20100818143801.GA9086@localhost> <20100818144655.GX2370@arachsys.com> <20100818152103.GA11268@localhost> <1282147034.77481.33.camel@useless.localdomain> <20100818155825.GA2370@arachsys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Lee Schermerhorn , Wu Fengguang , Minchan Kim , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , KOSAKI Motohiro , Pekka Enberg , Andi Kleen List-ID: Christoph Lameter writes: > On Wed, 18 Aug 2010, Chris Webb wrote: > > > > != 0. And even then, zone reclaim should only reclaim file pages, not > > > anon. In theory... > > > > Hi. This is zero on all our machines: > > > > # sysctl vm.zone_reclaim_mode > > vm.zone_reclaim_mode = 0 > > Set it to 1. I tried this on a handful of the problem hosts before re-adding their swap. One of them now runs without dipping into swap. The other three I tried had the same behaviour of sitting at zero swap usage for a while, before suddenly spiralling up with %wait going through the roof. I had to swapoff on them to bring them back into a sane state. So it looks like it helps a bit, but doesn't cure the problem. I could definitely believe an explanation that we're swapping in preference to allocating remote zone pages somehow, given the imbalance in free memory between the nodes which we saw. However, I read the documentation for vm.zone_reclaim_mode, which suggests to me that when it was set to zero, pages from remote zones should be allocated automatically in preference to swap given that zone_reclaim_mode & 4 == 0? Cheers, Chris. -- 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