Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756568AbYFBX4W (ORCPT ); Mon, 2 Jun 2008 19:56:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754858AbYFBX4O (ORCPT ); Mon, 2 Jun 2008 19:56:14 -0400 Received: from smtprelay10.ispgateway.de ([80.67.29.24]:45085 "EHLO smtprelay10.ispgateway.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753638AbYFBX4N (ORCPT ); Mon, 2 Jun 2008 19:56:13 -0400 From: Ingo Oeser To: Max Krasnyansky , Peter Zijlstra Subject: Re: Inquiry: Should we remove "isolcpus= kernel boot option? (may have realtime uses) Date: Tue, 3 Jun 2008 01:55:57 +0200 User-Agent: KMail/1.9.9 Cc: Paul Jackson , linux-kernel@vger.kernel.org, Con Kolivas , "Derek L. Fults" , devik , Dimitri Sivanich , Dinakar Guniguntala , Emmanuel Pacaud , Frederik Deweerdt , Ingo Molnar , Matthew Dobson , Nick Piggin , rostedt@goodmis.org, Oleg Nesterov , "Paul E. McKenney" , Paul Menage , "Randy.Dunlap" , suresh.b.siddha@intel.com, Thomas Gleixner References: <20080601213019.14ea8ef8.pj@sgi.com> <1212446707.6269.26.camel@lappy.programming.kicks-ass.net> <48447C75.8040203@qualcomm.com> In-Reply-To: <48447C75.8040203@qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200806030156.00155.ioe-lkml@rameria.de> X-Df-Sender: 849595 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1496 Lines: 37 Hi Max, Hi Peter, On Tuesday 03 June 2008, Max Krasnyansky wrote: > Ingo, I just wanted to elaborate on what Peter is saying. That CPU will still > have to be _booted_ properly. It may be used for hard- and soft- interrupt > processing, workqueues (internal kernel queuing mechanism) and kernel timers. Oh! Didn't know that user process scheduling is so much > In your particular case you're much much much better off with doing > echo 0 > /sys/devices/system/cpuN/online > either during initrd stage or as a first init script. > That way bad cpu will be _completely_ disabled. The initrd is from the distribution. I have no sane way to change it fast and permanent. Can I change the initrd and still have a certified RHEL or SLES? Are there initrd hooks, which survive packet installation? I would really appreciate some way to keep the kernel from using a CPU at all to do fault isolation. If possible not even booting it. Bootparameters survived all distro fiddling so far. I love them! Try to convince a hardware vendor, that you don't have a software bug. Try to convince him that you didn't break the hardware by swapping it around. So I'll ACK removing isolcpus, if we get a better replacement boot option. Best Regards Ingo Oeser -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/