Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759255AbXFUUYO (ORCPT ); Thu, 21 Jun 2007 16:24:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753194AbXFUUX6 (ORCPT ); Thu, 21 Jun 2007 16:23:58 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:48638 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752894AbXFUUX5 (ORCPT ); Thu, 21 Jun 2007 16:23:57 -0400 Date: Thu, 21 Jun 2007 22:23:14 +0200 From: Ingo Molnar To: Linus Torvalds Cc: Eric Dumazet , Chuck Ebbert , Jarek Poplawski , Miklos Szeredi , chris@atlee.ca, linux-kernel@vger.kernel.org, tglx@linutronix.de, akpm@linux-foundation.org Subject: Re: [BUG] long freezes on thinkpad t60 Message-ID: <20070621202314.GA32051@elte.hu> References: <20070621073031.GA683@elte.hu> <20070621160817.GA22897@elte.hu> <467AAB04.2070409@redhat.com> <20070621202917.a2bfbfc7.dada1@cosmosbay.com> <20070621195659.GA22303@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1196 Lines: 29 * Linus Torvalds wrote: > On Thu, 21 Jun 2007, Ingo Molnar wrote: > > > > I can understand why no data is saved by this change: gcc is > > aligning the next field to a natural boundary anyway and we dont > > really have arrays of spinlocks (fortunately). > > Actually, some data structures could well shrink. > > Look at "struct task_struct", for example. Right now it has two > spinlocks right next to each other (alloc_lock and pi_lock). yeah. We've got init_task's task-struct embedded in the vmlinux, but it's aligned to 32 bytes, which probably hides this effect. We'd only see it if the size change just happened to bring a key data structure (which is also embedded in the vmlinux) just below a modulo 32 bytes boundary. The chance for that is around 6:32 per 'merge' event. That means that there cannot be all that many such cases ;-) anyway, the shorter init sequence is worth it already. 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/