Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751839AbXACBGk (ORCPT ); Tue, 2 Jan 2007 20:06:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752708AbXACBGk (ORCPT ); Tue, 2 Jan 2007 20:06:40 -0500 Received: from mx1.redhat.com ([66.187.233.31]:50507 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751839AbXACBGk (ORCPT ); Tue, 2 Jan 2007 20:06:40 -0500 Date: Tue, 2 Jan 2007 20:06:31 -0500 From: Dave Jones To: Bodo Eggert <7eggert@gmx.de> Cc: mingo@redhat.com, Linux Kernel Subject: Re: Shrink the held_lock struct by using bitfields. Message-ID: <20070103010631.GA11031@redhat.com> Mail-Followup-To: Dave Jones , Bodo Eggert <7eggert@gmx.de>, mingo@redhat.com, Linux Kernel References: <7z1oG-6Jr-5@gated-at.bofh.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 956 Lines: 34 On Wed, Jan 03, 2007 at 01:47:36AM +0100, Bodo Eggert wrote: > Dave Jones wrote: > > > Shrink the held_lock struct by using bitfields. > > This shrinks task_struct on lockdep enabled kernels by 480 bytes. > > > * The following field is used to detect when we cross into an > > * interrupt context: > > */ > > - int irq_context; > [...] > > + unsigned char irq_context:1; > [...] > > Can these fields be set by concurrent processes, e.g.: > CPU0 CPU1 > load flags > load flags > flip bit > store > flip bit > store It's a per-process structure. Dave -- http://www.codemonkey.org.uk - 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/