Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261787AbTEMWdq (ORCPT ); Tue, 13 May 2003 18:33:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261849AbTEMWdq (ORCPT ); Tue, 13 May 2003 18:33:46 -0400 Received: from nmail1.systems.pipex.net ([62.241.160.130]:56260 "EHLO nmail1.systems.pipex.net") by vger.kernel.org with ESMTP id S261787AbTEMWdo (ORCPT ); Tue, 13 May 2003 18:33:44 -0400 To: Andrew Morton Subject: Re: 2.6 must-fix list, v2 Message-ID: <1052865981.3ec175bd59bc9@netmail.pipex.net> Date: Tue, 13 May 2003 23:46:21 +0100 From: "Shaheed R. Haque" Cc: References: <1050146434.3e97f68300fff@netmail.pipex.net> <1050177383.3e986f67b7f68@netmail.pipex.net> <1050177751.2291.468.camel@localhost> <1050222609.3e992011e4f54@netmail.pipex.net> <1050244136.733.3.camel@localhost> <1052826556.3ec0dbbc1d993@netmail.pipex.net> <20030513130257.78ab1a2e.akpm@digeo.com> In-Reply-To: <20030513130257.78ab1a2e.akpm@digeo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT User-Agent: PIPEX NetMail 2.2.0-pre13 X-PIPEX-username: aozw65%dsl.pipex.com X-Originating-IP: 81.86.202.62 X-Usage: Use of PIPEX NetMail is subject to the PIPEX Terms and Conditions of use Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1154 Lines: 31 Quoting Andrew Morton : > "Shaheed R. Haque" wrote: > > > > - Add ability to restrict the the default CPU affinity mask so that > > sys_setaffinity() can be used to implement exclusive access to a CPU. > > Why is this useful? Because it allows one to dedicate a CPU to a process. For example, lets say you have a quad processor,and want to run joe-random stuff on CPU 0, but a specialised program on CPUs 1, 2, 3 that does not want to compete with joe-random stuff. With sys_setaffinity(), one can set the affinity of the special program to 0xe...but the default affinity for all the joe-random stuff is still 0xf (from cpu_online_map)! Since its impractical to to modify every single joe-random executable to set its affinity to 0x1, a way is needed to set the default. The logical place is in init(), a.k.a. kernel/fork.c. I hope that make sense. Thanks, Shaheed - 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/