From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755982AbZENUXg (ORCPT ); Thu, 14 May 2009 16:23:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753352AbZENUX1 (ORCPT ); Thu, 14 May 2009 16:23:27 -0400 Received: from mx2.redhat.com ([66.187.237.31]:43826 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752881AbZENUX0 (ORCPT ); Thu, 14 May 2009 16:23:26 -0400 Message-ID: <4A0C7DB6.6010601@redhat.com> Date: Thu, 14 May 2009 16:23:18 -0400 From: Rik van Riel User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Christoph Lameter CC: Robin Holt , KOSAKI Motohiro , LKML , linux-mm , Andrew Morton Subject: Re: [PATCH 4/4] zone_reclaim_mode is always 0 by default References: <20090513120155.5879.A69D9226@jp.fujitsu.com> <20090513120729.5885.A69D9226@jp.fujitsu.com> <20090513152256.GM7601@sgi.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christoph Lameter wrote: > Not having zone reclaim on a NUMA system often means that per node > allocations will fall back. Optimized node local allocations become very > difficult for the page allocator. If the latency penalties are not > significant then this may not matter. The larger the system, the larger > the NUMA latencies become. > > One possibility would be to disable zone reclaim for low node numbers. > Eanble it only if more than 4 nodes exist? I suspect that patches 1/4 through 3/4 will cause the system to behave better already, by only reclaiming the easiest to reclaim pages from zone reclaim and falling back after that - or am overlooking something?