Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763498AbZD3Okd (ORCPT ); Thu, 30 Apr 2009 10:40:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752842AbZD3OkX (ORCPT ); Thu, 30 Apr 2009 10:40:23 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:37530 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752499AbZD3OkW (ORCPT ); Thu, 30 Apr 2009 10:40:22 -0400 Date: Thu, 30 Apr 2009 16:38:19 +0200 From: Ingo Molnar To: Christoph Lameter Cc: Mathieu Desnoyers , Linus Torvalds , Andrew Morton , Nick Piggin , KOSAKI Motohiro , Peter Zijlstra , thomas.pi@arcor.dea, Yuriy Lalym , Linux Kernel Mailing List , ltt-dev@lists.casi.polymtl.ca, Tejun Heo Subject: Re: [PATCH] Fix dirty page accounting in redirty_page_for_writepage() Message-ID: <20090430143819.GF14696@elte.hu> References: <20090429232546.GB15782@Krystal> <20090430024303.GB19875@Krystal> <20090430133859.GB8329@elte.hu> <20090430141446.GD14696@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1150 Lines: 31 * Christoph Lameter wrote: > On Thu, 30 Apr 2009, Ingo Molnar wrote: > > > The patch below makes the fallback/slowpath irq safe. > > Yes but sometimes you are already irq safe and such a fallback > would create significant irq/enable/disable stack operations etc > overhead for architectures that are using the fallback. It's a fallback slowpath - non-x86 architectures should still fill in a real implementation of course. > I think we really need another __xxx op here. Especially since > these operations are often in critical code paths. That's a receipe for fragility: as using __xxx will still be irq-safe on x86, and 95% of the testing is done on x86, so this opens up the path to non-x86 bugs. So we first have to see the list of architectures that _cannot_ implement an irq-safe op here via a single machine instruction. x86, ia64 and powerpc should be fine. Ingo -- 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/