From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759310AbYFJVsr (ORCPT ); Tue, 10 Jun 2008 17:48:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753353AbYFJVsk (ORCPT ); Tue, 10 Jun 2008 17:48:40 -0400 Received: from one.firstfloor.org ([213.235.205.2]:52851 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753050AbYFJVsj (ORCPT ); Tue, 10 Jun 2008 17:48:39 -0400 Message-ID: <484EF6B2.8010508@firstfloor.org> Date: Tue, 10 Jun 2008 23:48:34 +0200 From: Andi Kleen User-Agent: Thunderbird 1.5.0.12 (X11/20060911) MIME-Version: 1.0 To: Andrew Morton CC: Rik van Riel , clameter@sgi.com, linux-kernel@vger.kernel.org, lee.schermerhorn@hp.com, kosaki.motohiro@jp.fujitsu.com, linux-mm@kvack.org, eric.whitney@hp.com, Paul Mundt , Ingo Molnar , Andy Whitcroft Subject: Re: [PATCH -mm 13/25] Noreclaim LRU Infrastructure References: <20080606202838.390050172@redhat.com> <20080606202859.291472052@redhat.com> <20080606180506.081f686a.akpm@linux-foundation.org> <20080608163413.08d46427@bree.surriel.com> <20080608135704.a4b0dbe1.akpm@linux-foundation.org> <20080608173244.0ac4ad9b@bree.surriel.com> <20080608162208.a2683a6c.akpm@linux-foundation.org> <20080608193420.2a9cc030@bree.surriel.com> <20080608165434.67c87e5c.akpm@linux-foundation.org> <20080610153702.4019e042@cuia.bos.redhat.com> <20080610143334.c53d7d8a.akpm@linux-foundation.org> In-Reply-To: <20080610143334.c53d7d8a.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > Maybe it's time to bite the bullet and kill i386 NUMA support. afaik > it's just NUMAQ and a 2-node NUMAish machine which IBM made (as400?) Actually much more (most 64bit NUMA systems can run 32bit too), it just doesn't work well because the code is not very good, undertested, many bugs, weird design and in general 32bit NUMA has a lot of limitations that don't make it a good idea. But you don't need to kill it only for this (although imho there are lots of other good reasons) Just use a different way to look up the node. Encoding it into the flags is just an optimization. But a separate hash or similar would also work. It seemed like a good idea back then. In fact there's already a hash for this (the pa->node hash) that can do it. It' just some more instructions and one cache line more accessed, but since i386 NUMA is a fringe application that doesn't seem like a big issue. -Andi