From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752724AbZKLL1d (ORCPT ); Thu, 12 Nov 2009 06:27:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751592AbZKLL1c (ORCPT ); Thu, 12 Nov 2009 06:27:32 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:55251 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751423AbZKLL1c (ORCPT ); Thu, 12 Nov 2009 06:27:32 -0500 Date: Thu, 12 Nov 2009 12:27:34 +0100 From: Ingo Molnar To: Peter Zijlstra Cc: Mike Galbraith , LKML Subject: Re: [patch] sched: fix/add missing update_rq_clock() calls Message-ID: <20091112112734.GE24684@elte.hu> References: <1258020464.6491.2.camel@marge.simson.net> <1258023705.4039.103.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1258023705.4039.103.camel@laptop> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Peter Zijlstra wrote: > On Thu, 2009-11-12 at 11:07 +0100, Mike Galbraith wrote: > > sched: fix/add missing update_rq_clock() calls. > > > > kthread_bind(), migrate_task() and sched_fork were missing updates, and > > try_to_wake_up() was updating after having already used the stale clock. > > > I'm almost at the point where I think we should ditch rq->clock > alltogether and simply call cpu_clock() directly when we need it. This > trying to optimize and avoid calling it game has brought way too many > head-aches. It's not just about optimization - it's also accounting precision - we want to handle the full act of schedule() at a single timestamp - not a series of timestamps. But ... we can get rid of it if it can be done sanely. Ingo