From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758576AbYEWPHV (ORCPT ); Fri, 23 May 2008 11:07:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757902AbYEWPGs (ORCPT ); Fri, 23 May 2008 11:06:48 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:49190 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757280AbYEWPGo (ORCPT ); Fri, 23 May 2008 11:06:44 -0400 Date: Fri, 23 May 2008 17:06:22 +0200 From: Ingo Molnar To: Vegard Nossum Cc: Pekka Enberg , linux-kernel@vger.kernel.org Subject: Re: [PATCH] kmemcheck: SMP support Message-ID: <20080523150622.GA9782@elte.hu> References: <20080523141759.GA1833@damson.getinternet.no> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080523141759.GA1833@damson.getinternet.no> 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 * Vegard Nossum wrote: > This works on real hw, but not on qemu. It seems to get stuck waiting > for one of the atomic values to change. Don't know why yet, it might > just be yet another bug in qemu... (we've hit at least two of them so > far. And they were real bugs too.) > > But do you think this approach is feasible? It will kill > interactivity, that's for sure, though only when kmemcheck is run-time > enabled and number of CPUs > 1 (the more the worse). i think we definitely want it - if for no other purpose but for people to become disgusted at the overhead and fixing it ;-) Vegard, wanna have a look at introducing per CPU kernel pagetables? I tried that once in the past and it wasnt too horrible. (the patches are gone though) We could do it before bringing other CPUs online, i.e. much of the really yucky boot time pagetable juggling phase would be over already. Hm? Ingo