From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751254AbZKZBbH (ORCPT ); Wed, 25 Nov 2009 20:31:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750793AbZKZBbG (ORCPT ); Wed, 25 Nov 2009 20:31:06 -0500 Received: from mail.gmx.net ([213.165.64.20]:37905 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1750767AbZKZBbF (ORCPT ); Wed, 25 Nov 2009 20:31:05 -0500 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1+UA8tloNeUAyjMDOmhqZ7dx2k1wdrVWovTAc8lOz hfUd0CpCkZ6y/a Subject: Re: [patch] sched: fix set_task_cpu() and provide an unlocked runqueue variant From: Mike Galbraith To: Peter Zijlstra Cc: Ingo Molnar , LKML In-Reply-To: <1259197270.6186.17.camel@marge.simson.net> References: <1258891781.14325.34.camel@marge.simson.net> <1259173672.4027.732.camel@laptop> <1259197270.6186.17.camel@marge.simson.net> Content-Type: text/plain Date: Thu, 26 Nov 2009 02:31:08 +0100 Message-Id: <1259199068.6186.33.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 X-FuHaFi: 0.7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2009-11-26 at 02:01 +0100, Mike Galbraith wrote: > On Wed, 2009-11-25 at 19:27 +0100, Peter Zijlstra wrote: > > I've got to ask, what's that barrier for? > > It's a leftover from frustrated bug hunting. To be more specific, I put it there to ensure that min_vruntimes are stable. I figured that if try_to_wake_up() needs a barrier to look at task->state, I had better do the same for the runqueues. -Mike