From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755836AbXJHMec (ORCPT ); Mon, 8 Oct 2007 08:34:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754468AbXJHMdn (ORCPT ); Mon, 8 Oct 2007 08:33:43 -0400 Received: from cantor2.suse.de ([195.135.220.15]:58808 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754360AbXJHMdl (ORCPT ); Mon, 8 Oct 2007 08:33:41 -0400 From: Andi Kleen Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg) To: Ingo Molnar Subject: Re: [PATCH] [5/6] scheduler: Protect important kernel threads against normalize_rt Date: Mon, 8 Oct 2007 14:33:34 +0200 User-Agent: KMail/1.9.6 Cc: linux-kernel@vger.kernel.org References: <200710071059.126674000@suse.de> <20071007205958.7D8C41474B@wotan.suse.de> <20071008115142.GE22199@elte.hu> In-Reply-To: <20071008115142.GE22199@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200710081433.34845.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Monday 08 October 2007 13:51:42 Ingo Molnar wrote: > > * Andi Kleen wrote: > > > Not only the migration thread, but also softlockup and stop machine > > need to be protected against normalize_rt(). Instead of checking for > > them all I added a new process flag for this. > > hm, i dont really like this. The migration thread is an absolute > exception because it's needed for a correct scheduler. SysRq-N is like > SysRq-U or SysRq-B - last-minute resort in case something Goes Foul. > Results are not guaranteed. softlockup is the same. Just think about it. If you ever renormalize it and then run a fifo thread it will starve and then eventually kill the box. And starving CPU unplug is also equally bad. -Andi