From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933834AbYB2T6V (ORCPT ); Fri, 29 Feb 2008 14:58:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758666AbYB2T6I (ORCPT ); Fri, 29 Feb 2008 14:58:08 -0500 Received: from wolverine01.qualcomm.com ([199.106.114.254]:36956 "EHLO wolverine01.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758347AbYB2T6H (ORCPT ); Fri, 29 Feb 2008 14:58:07 -0500 X-IronPort-AV: E=McAfee;i="5200,2160,5242"; a="1036155" Message-ID: <47C863CB.404@qualcomm.com> Date: Fri, 29 Feb 2008 11:58:03 -0800 From: Max Krasnyanskiy User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Ingo Molnar CC: Jason Baron , Mathieu Desnoyers , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Rusty Russell , Peter Zijlstra Subject: Re: [patch 1/2] add ALL_CPUS option to stop_machine_run() References: <20080202210828.840735763@polymtl.ca> <20080202211204.268876860@polymtl.ca> <20080226225242.GA15926@redhat.com> <20080227190519.GA14335@Krystal> <20080228163303.GA6195@redhat.com> <47C73121.2000109@qualcomm.com> <20080229090050.GA19519@elte.hu> <47C84DCD.5040803@qualcomm.com> <20080229191559.GA18339@elte.hu> In-Reply-To: <20080229191559.GA18339@elte.hu> 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 Ingo Molnar wrote: > * Max Krasnyanskiy wrote: > >> btw Being an RT guy you do not think that stop machine is evil ? [...] > > i'm not "an RT guy", -rt is just one of the many projects i've been > involved with. > > and no, i dont think stop machine is "evil" - it's currently the best > way to do certain things. If you can solve it better then sure, i'm > awaiting your patches - but the only patch i saw from you so far was the > one that turned off stop-machine for isolated cpus - which was > incredibly broken and ignored the problem altogether. Ingo, I got it. My patch was a hack. Moving on. Seriously there is no need to say it ten thousand times ;-). You clipped the part where I elaborated what exactly is evil about the stop machine. I clearly said that yes for some things there is just no other way but in general we should _try_ to avoid it. Note that I did not say "we must" I'm saying we should try. > Right now the answer is: "if you want to do hard RT then avoid doing > things like loading modules". (which you should avoid while doing > hard-RT anyway) That's just not practical. Sure you can have some kind of stripped down machine but then you loose a lot of flexibility. Again "should" is the keyword here. For a lot of workloads hard-RT has to coexist with a bunch of other things. Max