From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759550AbYB0X5d (ORCPT ); Wed, 27 Feb 2008 18:57:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752646AbYB0X5X (ORCPT ); Wed, 27 Feb 2008 18:57:23 -0500 Received: from wolverine02.qualcomm.com ([199.106.114.251]:37443 "EHLO wolverine02.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751755AbYB0X5W (ORCPT ); Wed, 27 Feb 2008 18:57:22 -0500 X-IronPort-AV: E=McAfee;i="5200,2160,5239"; a="857650" Message-ID: <47C5F8E0.3060708@qualcomm.com> Date: Wed, 27 Feb 2008 15:57:20 -0800 From: Max Krasnyanskiy User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Peter Zijlstra CC: Ingo Molnar , Thomas Gleixner , Oleg Nesterov , Steven Rostedt , Paul Jackson , linux-kernel@vger.kernel.org Subject: Re: [RFC/PATCH 1/4] sched: remove isolcpus References: <20080227222103.673194000@chello.nl> <20080227222542.056473000@chello.nl> In-Reply-To: <20080227222542.056473000@chello.nl> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Zijlstra wrote: > cpu isolation doesn't offer anything over cpusets, hence remove it. Works for me. That's what I suggested in my reply to your comments. Here is the quote from the previous thread: >>>> This also allows for isolated groups, there are good reasons to isolate groups, >>>> esp. now that we have a stronger RT balancer. SMP and hard RT are not >>>> exclusive. A design that does not take that into account is too rigid. >> >>> You're thinking scheduling only. Paul had the same confusion ;-) >> >> I'm not, I'm thinking it ought to allow for it. > One way I can think of how to support groups and allow for RT balancer is > this: Make scheduler ignore cpu_isolated_map and give cpusets full control of > the scheduler domains. Use cpu_isolated_map to only for hw irq and other > kernel sub-systems. That way cpusets could mark cpus in the group as isolated > to get rid of the kernel activity and build sched domain such that tasks get > balanced in it. > The thing I do not like about it is that there is no way to boot the system > with CPU N isolated from the beginning. Also dynamic isolation currently > relies on the cpu hotplug to clear pending irqs, softirqs, kernel timers and > threads. So cpusets would have to simulate the cpu hotplug event I guess. Max