From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946027AbWJaX6l (ORCPT ); Tue, 31 Oct 2006 18:58:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1946176AbWJaX6l (ORCPT ); Tue, 31 Oct 2006 18:58:41 -0500 Received: from omx1-ext.sgi.com ([192.48.179.11]:26807 "EHLO omx1.americas.sgi.com") by vger.kernel.org with ESMTP id S1946027AbWJaX6k (ORCPT ); Tue, 31 Oct 2006 18:58:40 -0500 Date: Tue, 31 Oct 2006 15:58:19 -0800 From: Paul Jackson To: Paul Jackson Cc: dino@in.ibm.com, nickpiggin@yahoo.com.au, akpm@osdl.org, mbligh@google.com, menage@google.com, Simon.Derr@bull.net, linux-kernel@vger.kernel.org, rohitseth@google.com, holt@sgi.com, dipankar@in.ibm.com, suresh.b.siddha@intel.com Subject: Re: [RFC] cpuset: Explicit dynamic sched domain cpuset flag Message-Id: <20061031155819.29621173.pj@sgi.com> In-Reply-To: <20061031064300.10a97c13.pj@sgi.com> References: <20061030212615.GA10567@in.ibm.com> <20061030212922.GA20369@in.ibm.com> <20061031064300.10a97c13.pj@sgi.com> Organization: SGI X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.3; 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 pj wrote: > 9) Finally, we really do need a way, on a production system, for user > space to ask the kernel where load balancing is limited. > > For example one possible interface would have user space pass a > cpumask to the kernel, and get back a Boolean value, indicating > whether or not there are any limitations on load balancing between > any two CPUs specified in that cpumask. Ah - a simpler API, more user friendly, more "cpuset API style" friendly: A read-only, per-cpuset Boolean flag that indicates whether the scheduler is fully load balancing across all 'cpus' of that cpuset. Internally, the kernel would answer this by seeing whether or not the cpusets cpus_allowed cpumask was a subset of one of the members of the scheduler domains partition. Call this per-cpuset flag something such as: sched_is_fully_load_balanced # read-only Boolean This goes along with having the control flag named something such as: sched_ok_not_to_load_balance # read-write Boolean If a task was in a cpuset that had 'sched_is_fully_load_balanced' False, then it might not get load balanced. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.925.600.0401