From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262174AbVDWX3u (ORCPT ); Sat, 23 Apr 2005 19:29:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262175AbVDWX3t (ORCPT ); Sat, 23 Apr 2005 19:29:49 -0400 Received: from omx2-ext.sgi.com ([192.48.171.19]:52893 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S262174AbVDWX32 (ORCPT ); Sat, 23 Apr 2005 19:29:28 -0400 Date: Sat, 23 Apr 2005 16:26:40 -0700 From: Paul Jackson To: nickpiggin@yahoo.com.au Cc: dino@in.ibm.com, Simon.Derr@bull.net, linux-kernel@vger.kernel.org, lse-tech@lists.sourceforge.net, akpm@osdl.org, dipankar@in.ibm.com, colpatch@us.ibm.com Subject: Re: [RFC PATCH] Dynamic sched domains aka Isolated cpusets Message-Id: <20050423162640.69ccbabc.pj@sgi.com> In-Reply-To: <20050419133431.2e389d57.pj@sgi.com> References: <1097110266.4907.187.camel@arrakis> <20050418202644.GA5772@in.ibm.com> <20050418225427.429accd5.pj@sgi.com> <1113891575.5074.46.camel@npiggin-nld.site> <20050419001926.605a6b59.pj@sgi.com> <1113897440.5074.62.camel@npiggin-nld.site> <20050419133431.2e389d57.pj@sgi.com> 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 A few days ago, Nick wrote: > Well the scheduler simply can't handle it, so it is not so much a > matter of pushing - you simply can't use partitioned domains and > meaningfully have a cpuset above them. And I (pj) replied: > Translating that into cpuset-speak, I think what you mean is ... I then went on to ask some questions. I haven't seen a reply. I probably wrote too many words, and you had more pressing matters to deal with. Which is fine. Let's make this simpler. Ignore cpusets -- let's just talk about a tasks cpus_allowed value, and scheduler domains. Think of cpusets as just a strange way of setting a tasks cpus_allowed value. Question: What happens if we have say two isolated scheduler domains on a system, covering say two halves of the system, and some task has its cpus_allowed set to allow _all_ CPUs? What kind of pain does that cause? I'm hoping you will say that the only pain it causes is that the task will only run on one half of the system, even if the other half is idle. And that so long as I don't mind that, it's no problem to do this. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.650.933.1373, 1.925.600.0401