From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262743AbVCJU5J (ORCPT ); Thu, 10 Mar 2005 15:57:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262848AbVCJU5J (ORCPT ); Thu, 10 Mar 2005 15:57:09 -0500 Received: from omx2-ext.sgi.com ([192.48.171.19]:6551 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S262743AbVCJU4e (ORCPT ); Thu, 10 Mar 2005 15:56:34 -0500 Date: Thu, 10 Mar 2005 12:54:48 -0800 From: Paul Jackson To: Dave Hansen Cc: mel@csn.ul.ie, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] 0/2 Buddy allocator with placement policy (Version 9) + prezeroing (Version 4) Message-Id: <20050310125448.5b52dcba.pj@engr.sgi.com> In-Reply-To: <1110485835.24355.1.camel@localhost> References: <20050307193938.0935EE594@skynet.csn.ul.ie> <1110239966.6446.66.camel@localhost> <20050310092201.37bae9ba.pj@engr.sgi.com> <1110478613.16432.36.camel@localhost> <20050310121124.488cb7c5.pj@engr.sgi.com> <1110485835.24355.1.camel@localhost> Organization: SGI X-Mailer: Sylpheed version 1.0.0 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Dave wrote: > Shouldn't a particular task know what the policy should be when it is > launched? No ... but not necessarily because it isn't known yet, but rather also because it might be imposed earlier in the job creation, before the actual task hierarchy is manifest. This point goes to the heart of one of the motivations for cpusets themselves. On a big system, one might have OpenMP threads inside MPI tasks inside jobs being managed by a batch manager, running on a subset of the system. The system admins may need to impose these policy decisions from the outside, and not uniformly across the entire batch managed arena. The cpuset becomes the named object, to which such attributes accrue, to take affect on whatever threads, tasks, or jobs end up thereon. Do a google search for "mixed openmp mpi", or for "hybrid openmp mpi", to find examples of such usage, then imagine such jobs running inside a batch manager, on a portion of a larger system. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.650.933.1373, 1.925.600.0401