Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S271032AbUJUXGF (ORCPT ); Thu, 21 Oct 2004 19:06:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S271092AbUJUXFD (ORCPT ); Thu, 21 Oct 2004 19:05:03 -0400 Received: from mail.timesys.com ([65.117.135.102]:40620 "EHLO exchange.timesys.com") by vger.kernel.org with ESMTP id S271032AbUJUW43 (ORCPT ); Thu, 21 Oct 2004 18:56:29 -0400 Message-ID: <41783E4A.5020902@timesys.com> Date: Thu, 21 Oct 2004 18:55:06 -0400 From: john cooper User-Agent: Mozilla Thunderbird 0.8 (X11/20040913) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Scott Wood CC: "Eugeny S. Mints" , Esben Nielsen , Ingo Molnar , Thomas Gleixner , Jens Axboe , Rui Nuno Capela , LKML , Lee Revell , mark_h_johnson@raytheon.com, "K.R. Foley" , Bill Huey , Adam Heath , Florian Schmidt , Michal Schmidt , Fernando Pablo Lopez-Lezcano , john cooper Subject: Re: [patch] Real-Time Preemption, -RT-2.6.9-rc4-mm1-U8 References: <4177CD3C.9020201@timesys.com> <4177DA11.4090902@ru.mvista.com> <4177E89A.1090100@timesys.com> <20041021173302.GA26318@yoda.timesys> <4177FB4F.9030202@timesys.com> <20041021184742.GB26530@yoda.timesys> <41781984.5090602@timesys.com> <20041021211244.GA28290@yoda.timesys> <417834E4.7000506@timesys.com> <20041021223003.GA28704@yoda.timesys> In-Reply-To: <20041021223003.GA28704@yoda.timesys> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 21 Oct 2004 22:51:18.0375 (UTC) FILETIME=[7A202F70:01C4B7C0] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1051 Lines: 31 Scott Wood wrote: >On Thu, Oct 21, 2004 at 06:15:00PM -0400, john cooper wrote: > >>Yes, but my concern was having to backoff in out-of-sequence >>spinlock acquisition paths. >> > >Out-of-sequence acquisition is a bug, unless the caller uses trylocks >and handles backoff itself. > Understood -- we may be getting hung up on terminology here. Rather the issue was whether the nondeterministic out-of-sequence backoff could be pushed to a noncritical path. I believe so. It is further likely a backoff would not be needed as the a path acquiring a mutex's task-owned list lock during a priority promotion scan shouldn't have reason to acquire any task's mutex-owned list lock. The latter list would only need to be locked at time of successful mutex acquisition/free. -john -- john.cooper@timesys.com - 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/