From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757953AbXHBPTc (ORCPT ); Thu, 2 Aug 2007 11:19:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756852AbXHBPTW (ORCPT ); Thu, 2 Aug 2007 11:19:22 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:44936 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757371AbXHBPTV (ORCPT ); Thu, 2 Aug 2007 11:19:21 -0400 Date: Thu, 2 Aug 2007 17:19:16 +0200 From: Ingo Molnar To: Martin Roehricht Cc: linux-kernel@vger.kernel.org Subject: Re: Scheduling the highest priority task Message-ID: <20070802151916.GA8688@elte.hu> References: <8KLFD-G9-5@gated-at.bofh.it> <46B19CA1.7050204@felicis.org> <20070802114012.GA4067@elte.hu> <46B1F182.3010608@felicis.org> <20070802150350.GA3030@elte.hu> <46B1F4BA.4010107@felicis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <46B1F4BA.4010107@felicis.org> User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -1.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Martin Roehricht wrote: > That's fine with me, that within the same priority-queue any task can > be chosen. But assume two tasks with highly different priorities, such > as 105 and 135 are scheduled on the same processor and one of them is > now to be migrated -- shouldn't be the queue with task P=105 > considered first for migration by this code? Both tasks would use > different queues with their own linked lists, right? yes. What makes you believe that the lower priority one (prio 135) is chosen? [ as i said before, that will only be chosen if all tasks in the higher-priority queue (prio 105) are either already running on a CPU or have recently run so that the cache-hot logic skips them. ] Ingo