From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750852AbWFGNW1 (ORCPT ); Wed, 7 Jun 2006 09:22:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750882AbWFGNW1 (ORCPT ); Wed, 7 Jun 2006 09:22:27 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:55702 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S1750852AbWFGNW0 (ORCPT ); Wed, 7 Jun 2006 09:22:26 -0400 Date: Wed, 7 Jun 2006 15:21:55 +0200 From: Ingo Molnar To: Benjamin Herrenschmidt Cc: Andrew Morton , linux-kernel@vger.kernel.org, paulus@samba.org Subject: Re: mutex vs. local irqs (Was: 2.6.18 -mm merge plans) Message-ID: <20060607132155.GB14425@elte.hu> References: <20060604135011.decdc7c9.akpm@osdl.org> <1149652378.27572.109.camel@localhost.localdomain> <20060606212930.364b43fa.akpm@osdl.org> <1149656647.27572.128.camel@localhost.localdomain> <20060606222942.43ed6437.akpm@osdl.org> <1149662671.27572.158.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1149662671.27572.158.camel@localhost.localdomain> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -3.1 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-3.1 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.0 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.5000] 0.2 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Benjamin Herrenschmidt wrote: > during boot). In addition to that, archs need to add something to their > actual interrupt entry: > > if (no_irq_boot) { > local_irq_disable(); > return; > } that just moves the suckage from the mutex-debugging slowpath to the irq-handling hotpath. (at which point i still prefer to have that in the mutex-debugging path) a better solution would be to install boot-time IRQ vectors that just do nothing but return. They dont mask, they dont ACK nor EOI - they just return. The only thing that could break this is a screaming interrupt, and even that one probably just slows things down a tiny bit until we get so far in the init sequence to set up the PIC. Ingo