From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chris Friesen" Subject: Re: RFC: THE OFFLINE SCHEDULER Date: Wed, 26 Aug 2009 15:15:26 -0600 Message-ID: <4A95A5EE.90400@nortel.com> References: <1251282598.3514.20.camel@raz> <1251297910.1791.22.camel@maxim-laptop> <1251298443.4791.7.camel@raz> <1251300625.18584.18.camel@twins> <1251302598.18584.31.camel@twins> <20090826180407.GA13632@elte.hu> <20090826193252.GA14721@elte.hu> <20090826135041.e6169d18.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Christoph Lameter , mingo@elte.hu, peterz@infradead.org, raziebe@gmail.com, maximlevitsky@gmail.com, efault@gmx.de, riel@redhat.com, wiseman@macs.biu.ac.il, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org To: Andrew Morton Return-path: Received: from zrtps0kp.nortel.com ([47.140.192.56]:50773 "EHLO zrtps0kp.nortel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753367AbZHZVP4 (ORCPT ); Wed, 26 Aug 2009 17:15:56 -0400 In-Reply-To: <20090826135041.e6169d18.akpm@linux-foundation.org> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On 08/26/2009 02:50 PM, Andrew Morton wrote: > What problem? > > All I've seen is "I want 100% access to a CPU". That's not a problem > statement - it's an implementation. > > What is the problem statement? I can only speak for myself... In our case the problem statement was that we had an inherently single-threaded emulator app that we wanted to push as hard as absolutely possible. We gave it as close to a whole cpu as we could using cpu and irq affinity and we used message queues in shared memory to allow another cpu to handle I/O. In our case we still had kernel threads running on the app cpu, but if we'd had a straightforward way to avoid them we would have used it. Chris