From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756905AbXKAV2V (ORCPT ); Thu, 1 Nov 2007 17:28:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753350AbXKAV2L (ORCPT ); Thu, 1 Nov 2007 17:28:11 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:41522 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751674AbXKAV2K (ORCPT ); Thu, 1 Nov 2007 17:28:10 -0400 Date: Thu, 01 Nov 2007 14:28:09 -0700 (PDT) Message-Id: <20071101.142809.179954273.davem@davemloft.net> To: clameter@sgi.com Cc: dada1@cosmosbay.com, akpm@linux-foundation.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, mathieu.desnoyers@polymtl.ca, penberg@cs.helsinki.fi Subject: Re: [patch 0/7] [RFC] SLUB: Improve allocpercpu to reduce per cpu access overhead From: David Miller In-Reply-To: References: <20071101000211.970501947@sgi.com> <47297DA6.5070904@cosmosbay.com> X-Mailer: Mew version 5.2 on Emacs 22.1 / Mule 5.0 (SAKAKI) 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 From: Christoph Lameter Date: Thu, 1 Nov 2007 05:57:12 -0700 (PDT) > That is basically what IA64 is doing but it not usable because you would > have addresses that mean different things on different cpus. List head > for example require back pointers. If you put a listhead into such a per > cpu area then you may corrupt another cpus per cpu area. Indeed, but as I pointed out in another mail it actually works if you set some rules: 1) List insert and delete is only allowed on local CPU lists. 2) List traversal is allowed on remote CPU lists. I bet we could get all of the per-cpu users to abide by this rule if we wanted to. The remaining issue with accessing per-cpu areas at multiple virtual addresses is D-cache aliasing.