From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030270AbVLMWfW (ORCPT ); Tue, 13 Dec 2005 17:35:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030305AbVLMWfW (ORCPT ); Tue, 13 Dec 2005 17:35:22 -0500 Received: from omx2-ext.sgi.com ([192.48.171.19]:4078 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S1030270AbVLMWfV (ORCPT ); Tue, 13 Dec 2005 17:35:21 -0500 Date: Tue, 13 Dec 2005 14:35:00 -0800 From: Paul Jackson To: Eric Dumazet Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, nickpiggin@yahoo.com.au, Simon.Derr@bull.net, ak@suse.de, clameter@sgi.com Subject: Re: [PATCH] Cpuset: rcu optimization of page alloc hook Message-Id: <20051213143500.96c9aecd.pj@sgi.com> In-Reply-To: <439F2F39.3090800@cosmosbay.com> References: <20051211233130.18000.2748.sendpatchset@jackhammer.engr.sgi.com> <439D39A8.1020806@cosmosbay.com> <20051212020211.1394bc17.pj@sgi.com> <20051212021247.388385da.akpm@osdl.org> <20051213075345.c39f335d.pj@sgi.com> <439EF75D.50206@cosmosbay.com> <20051213120814.f7e1d73d.pj@sgi.com> <439F2F39.3090800@cosmosbay.com> Organization: SGI X-Mailer: Sylpheed version 2.1.7 (GTK+ 2.4.9; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Eric wrote: > But the initial pointer *should* be in a cache line shared by all cpus to get > best performance. No - not if that pointer is seldom used. Then its location does not directly affect performance at all, and better for it to be used as "inert filler" to fill out cache lines of words that are write hot. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.925.600.0401