Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757632AbXHUXO2 (ORCPT ); Tue, 21 Aug 2007 19:14:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754732AbXHUXOV (ORCPT ); Tue, 21 Aug 2007 19:14:21 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:59702 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751630AbXHUXOU (ORCPT ); Tue, 21 Aug 2007 19:14:20 -0400 Date: Tue, 21 Aug 2007 16:14:19 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Mathieu Desnoyers cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, mingo@redhat.com Subject: Re: [PATCH] SLUB use cmpxchg_local In-Reply-To: <20070821173849.GA8360@Krystal> Message-ID: References: <20070820201519.512791382@polymtl.ca> <20070820201822.597720007@polymtl.ca> <20070820204126.GA22507@Krystal> <20070820212922.GA27011@Krystal> <20070820215413.GA28452@Krystal> <20070821173849.GA8360@Krystal> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 667 Lines: 14 On Tue, 21 Aug 2007, Mathieu Desnoyers wrote: > - Changed smp_rmb() for barrier(). We are not interested in read order > across cpus, what we want is to be ordered wrt local interrupts only. > barrier() is much cheaper than a rmb(). But this means a preempt disable is required. RT users do not want that. Without preemption the processor can be moved after c has been determined. That is why the smp_rmb() is there. - 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/