Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764849AbXH0VZ4 (ORCPT ); Mon, 27 Aug 2007 17:25:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759338AbXH0VPQ (ORCPT ); Mon, 27 Aug 2007 17:15:16 -0400 Received: from tomts22-srv.bellnexxia.net ([209.226.175.184]:35020 "EHLO tomts22-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758353AbXH0VPO (ORCPT ); Mon, 27 Aug 2007 17:15:14 -0400 Date: Mon, 27 Aug 2007 17:10:03 -0400 From: Mathieu Desnoyers To: Christoph Lameter Cc: Peter Zijlstra , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, mingo@redhat.com Subject: Re: [PATCH] SLUB use cmpxchg_local Message-ID: <20070827211003.GA10627@Krystal> References: <20070820215413.GA28452@Krystal> <20070821173849.GA8360@Krystal> <1188197539.6114.426.camel@twins> <20070827202203.GB5653@Krystal> <20070827203913.GA7416@Krystal> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 17:08:55 up 28 days, 21:27, 7 users, load average: 1.10, 1.17, 1.05 User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1469 Lines: 39 * Christoph Lameter (clameter@sgi.com) wrote: > I think the simplest solution may be to leave slub as done in the patch > that we developed last week. The arch must provide a cmpxchg_local that is > performance wise the fastest possible. On x86 this is going to be the > cmpxchg_local on others where cmpxchg is slower than interrupt > disable/enable this is going to be the emulation that does > > interrupt disable > > cmpchg simulation > > interrupt enable > > > If we can establish that this is not a performance regression then we have > a clean solution source code wise. It also minimizes the interrupt holdoff > for the non-cmpxchg_local arches. However, it means that we will have to > disable interrupts twice for the slow path. If that is too expensive then > we need a different solution. > cmpxchg_local is not used on the slow path... ? Did you meant: it means that we will have to disable preemption _and_ interrupts on the fast path for non-cmpxchg_local arches ? Or maybe am I thinking about the wrong code snippet there ? -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/