Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262724AbVCXIsF (ORCPT ); Thu, 24 Mar 2005 03:48:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262727AbVCXIsF (ORCPT ); Thu, 24 Mar 2005 03:48:05 -0500 Received: from ms-smtp-03.nyroc.rr.com ([24.24.2.57]:45202 "EHLO ms-smtp-03.nyroc.rr.com") by vger.kernel.org with ESMTP id S262724AbVCXIsA (ORCPT ); Thu, 24 Mar 2005 03:48:00 -0500 Date: Thu, 24 Mar 2005 03:47:56 -0500 (EST) From: Steven Rostedt X-X-Sender: rostedt@localhost.localdomain Reply-To: rostedt@goodmis.org To: Ingo Molnar cc: linux-kernel@vger.kernel.org Subject: Re: [patch] Real-Time Preemption, -RT-2.6.12-rc1-V0.7.41-07 In-Reply-To: Message-ID: References: <20050321090622.GA8430@elte.hu> <20050322054345.GB1296@us.ibm.com> <20050322072413.GA6149@elte.hu> <20050322092331.GA21465@elte.hu> <20050322093201.GA21945@elte.hu> <20050322100153.GA23143@elte.hu> <20050322112856.GA25129@elte.hu> <20050323061601.GE1294@us.ibm.com> <20050323063317.GB31626@elte.hu> <20050324052854.GA1298@us.ibm.com> <20050324053456.GA14494@elte.hu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1101 Lines: 33 On Thu, 24 Mar 2005, Steven Rostedt wrote: > > I've noticed the following situation which is caused by __up_mutex > assigning an owner right away. > I also see this with non rt tasks causing a burst of schedules. 1. Process A runs and grabs lock L. then finishes its time slice. 2. Process B runs and tries to grab Lock L. 3. Process A runs and releases lock L. 4. __up_mutex gives process B lock L. 5. Process A tries to grab lock L. 6. Process B runs and releases lock L. 7. __up_mutex gives lock L to process A. 8. Process B tries to grab lock L again. 9. Process A runs... Here we have more unnecessary schedules. So the condition to grab a lock should be: 1. not owned. 2. partially owned, and the owner is not RT. 3. partially owned but the owner is RT and so is the grabber, and the grabber's priority is >= the owner's priority. -- Steve - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/