From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qa0-f44.google.com (mail-qa0-f44.google.com [209.85.216.44]) by kanga.kvack.org (Postfix) with ESMTP id A2A7E6B0031 for ; Thu, 10 Apr 2014 06:26:39 -0400 (EDT) Received: by mail-qa0-f44.google.com with SMTP id hw13so3632944qab.17 for ; Thu, 10 Apr 2014 03:26:39 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTP id b6si1666823qae.168.2014.04.10.03.26.38 for ; Thu, 10 Apr 2014 03:26:38 -0700 (PDT) Message-ID: <534671DB.50802@redhat.com> Date: Thu, 10 Apr 2014 11:26:35 +0100 From: Jeremy Harris MIME-Version: 1.0 Subject: Re: [PATCH 0/2] Disable zone_reclaim_mode by default References: <1396910068-11637-1-git-send-email-mgorman@suse.de> <5343A494.9070707@suse.cz> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: Cc: Linux-MM , LKML On 08/04/14 23:58, Christoph Lameter wrote: > The reason that zone reclaim is on by default is that off node accesses > are a big performance hit on large scale NUMA systems (like ScaleMP and > SGI). Zone reclaim was written *because* those system experienced severe > performance degradation. > > On the tightly coupled 4 and 8 node systems there does not seem to > be a benefit from what I hear. In principle, is this difference in distance something the kernel could measure? -- Cheers, Jeremy -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935351AbaDJK0k (ORCPT ); Thu, 10 Apr 2014 06:26:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44200 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933885AbaDJK0j (ORCPT ); Thu, 10 Apr 2014 06:26:39 -0400 Message-ID: <534671DB.50802@redhat.com> Date: Thu, 10 Apr 2014 11:26:35 +0100 From: Jeremy Harris User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 CC: Linux-MM , LKML Subject: Re: [PATCH 0/2] Disable zone_reclaim_mode by default References: <1396910068-11637-1-git-send-email-mgorman@suse.de> <5343A494.9070707@suse.cz> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/04/14 23:58, Christoph Lameter wrote: > The reason that zone reclaim is on by default is that off node accesses > are a big performance hit on large scale NUMA systems (like ScaleMP and > SGI). Zone reclaim was written *because* those system experienced severe > performance degradation. > > On the tightly coupled 4 and 8 node systems there does not seem to > be a benefit from what I hear. In principle, is this difference in distance something the kernel could measure? -- Cheers, Jeremy