From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762092AbYBMDdn (ORCPT ); Tue, 12 Feb 2008 22:33:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752078AbYBMDdg (ORCPT ); Tue, 12 Feb 2008 22:33:36 -0500 Received: from ithilien.qualcomm.com ([129.46.51.59]:46413 "EHLO ithilien.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751437AbYBMDdf (ORCPT ); Tue, 12 Feb 2008 22:33:35 -0500 Message-ID: <47B264E3.4090605@qualcomm.com> Date: Tue, 12 Feb 2008 19:32:51 -0800 From: Max Krasnyansky User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: David Miller CC: nickpiggin@yahoo.com.au, akpm@linux-foundation.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, mingo@elte.hu, pj@sgi.com, a.p.zijlstra@chello.nl, gregkh@suse.de, rusty@rustcorp.com.au Subject: Re: [git pull for -mm] CPU isolation extensions (updated2) References: <47B11C45.6060408@qualcomm.com> <200802121741.22201.nickpiggin@yahoo.com.au> <20080211.224436.174153780.davem@davemloft.net> In-Reply-To: <20080211.224436.174153780.davem@davemloft.net> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Miller wrote: > From: Nick Piggin > Date: Tue, 12 Feb 2008 17:41:21 +1100 > >> stop machine is used for more than just module loading and unloading. >> I don't think you can just disable it. > > Right, in particular it is used for CPU hotplug. Ooops. Totally missed that. And a bunch of other places. [maxk@duo2 cpuisol-2.6.git]$ git grep -l stop_machine_run Documentation/cpu-hotplug.txt arch/s390/kernel/kprobes.c drivers/char/hw_random/intel-rng.c include/linux/stop_machine.h kernel/cpu.c kernel/module.c kernel/stop_machine.c mm/page_alloc.c I wonder why I did not see any issues when I disabled stop machine completely. I mentioned in the other thread that I commented out the part that actually halts the machine and ran it for several hours on my dual core laptop and on the quad core server. Tried all kinds of workloads, which include constant module removal and insertion, and cpu hotplug as well. It cannot be just luck :). Clearly though, you guys are right. It cannot be simply disabled. Based on the above grep it's needed for CPU hotplug, mem hotplug, kprobes on s390 and intel rng driver. Hopefully we can avoid it at least in module insertion/removal. Max