From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763291AbYB1WOp (ORCPT ); Thu, 28 Feb 2008 17:14:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759551AbYB1WOe (ORCPT ); Thu, 28 Feb 2008 17:14:34 -0500 Received: from tomts16.bellnexxia.net ([209.226.175.4]:44157 "EHLO tomts16-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759247AbYB1WOd (ORCPT ); Thu, 28 Feb 2008 17:14:33 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Ao8CAIjAxkdMQWRV/2dsb2JhbACBVqxx Date: Thu, 28 Feb 2008 17:14:30 -0500 From: Mathieu Desnoyers To: Max Krasnyanskiy Cc: Jason Baron , akpm@linux-foundation.org, Ingo Molnar , linux-kernel@vger.kernel.org, Rusty Russell Subject: Re: [patch 1/2] add ALL_CPUS option to stop_machine_run() Message-ID: <20080228221430.GA22958@Krystal> References: <20080202210828.840735763@polymtl.ca> <20080202211204.268876860@polymtl.ca> <20080226225242.GA15926@redhat.com> <20080227190519.GA14335@Krystal> <20080228163303.GA6195@redhat.com> <47C73121.2000109@qualcomm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <47C73121.2000109@qualcomm.com> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 17:12:19 up 17 days, 18:12, 4 users, load average: 0.46, 0.56, 0.65 User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Max Krasnyanskiy (maxk@qualcomm.com) wrote: > Jason Baron wrote: >> -allow stop_mahcine_run() to call a function on all cpus. Calling >> stop_machine_run() with a 'ALL_CPUS' invokes this new behavior. >> stop_machine_run() proceeds as normal until the calling cpu has >> invoked 'fn'. Then, we tell all the other cpus to call 'fn'. > > Jason, we're actually trying to reduce the usage of the stop_machine in > general. It's a very big hammer that kills latencies and stuff. It'd be > nice if we did not introduce any more dependencies on it. I guess in some > case there is simply no other way to handle what need to do. But please > think twice > (or more :)). > > Max > > I have a "more complex" immediate value implementation that does not depend on such heavy lock. I made this simplified version because Rusty preferred it, although I say from the beginning that it kills interrupt latency. I could propose the atomic, nmi-safe version directly if enough people are in favor of it. Mathieu -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68