From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265970AbUGOAE6 (ORCPT ); Wed, 14 Jul 2004 20:04:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266004AbUGOAE6 (ORCPT ); Wed, 14 Jul 2004 20:04:58 -0400 Received: from mail-relay-4.tiscali.it ([213.205.33.44]:16568 "EHLO mail-relay-4.tiscali.it") by vger.kernel.org with ESMTP id S266001AbUGOAE4 (ORCPT ); Wed, 14 Jul 2004 20:04:56 -0400 Date: Thu, 15 Jul 2004 02:04:38 +0200 From: Andrea Arcangeli To: Peter Zaitsev Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: VM Problems in 2.6.7 (Too active OOM Killer) Message-ID: <20040715000438.GS974@dualathlon.random> References: <1089771823.15336.2461.camel@abyss.home> <20040714031701.GT974@dualathlon.random> <1089776640.15336.2557.camel@abyss.home> <20040713211721.05781fb7.akpm@osdl.org> <1089848823.15336.3895.camel@abyss.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1089848823.15336.3895.camel@abyss.home> X-GPG-Key: 1024D/68B9CB43 13D9 8355 295F 4823 7C49 C012 DFA1 686E 68B9 CB43 X-PGP-Key: 1024R/CB4660B9 CC A0 71 81 F4 A0 63 AC C0 4B 81 1D 8C 15 C8 E5 User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 14, 2004 at 04:47:04PM -0700, Peter Zaitsev wrote: > To be honest I do not really understand this OOM without swap problem at > all, why is it possible to move pages from ZONE_NORMAL to swap but not > to other zones ? the oom without swap you reproduced is not related to ZONE_NORMAL shortage. The pages in ZONE_NORMAL never goes into swap. the ZONE_NORMAL oom is a separate issue from the oom killing you reproduced. with 2.6.7 if you were hitting the ZONE_NORMAL shortage your machine would lockup and it would never oom-kill anything (Andrew just changed that in kernel CVS, so thanks to that change a ZONE_NORMAL shortage will not deadlock anymore in 2.6.8, but OTOH in 2.6.8 adding swap will not be enough anymore to workaround the oom-killing you reproduced). About the ZONE_NORMAL shortage without swap, rather than running cpu-cache-hungry memcopies from lowmemzone to highmem (or even worse to pass through swap like it happens in 2.6 mainline with swap enabled), I believe it's better to reserve some ram in the lowmem zone, 800M of ram on a 32G box should be a cheap price to pay compared to the cpu/IO cost involved in moving memory around during the bench.