Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965012AbVLQXnK (ORCPT ); Sat, 17 Dec 2005 18:43:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965003AbVLQXnJ (ORCPT ); Sat, 17 Dec 2005 18:43:09 -0500 Received: from palinux.external.hp.com ([192.25.206.14]:35749 "EHLO palinux.hppa") by vger.kernel.org with ESMTP id S964944AbVLQXnG (ORCPT ); Sat, 17 Dec 2005 18:43:06 -0500 Date: Sat, 17 Dec 2005 16:43:05 -0700 From: Matthew Wilcox To: Linus Torvalds Cc: Steven Rostedt , Joe Korty , Thomas Gleixner , Geert Uytterhoeven , Andrew Morton , linux-arch@vger.kernel.org, Linux Kernel Development , arjan@infradead.org, Christoph Hellwig , mingo@elte.hu, Alan Cox , nikita@clusterfs.com, pj@sgi.com, dhowells@redhat.com Subject: Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation Message-ID: <20051217234305.GH2361@parisc-linux.org> References: <1134769269.2806.17.camel@tglx.tec.linutronix.de> <1134770778.2806.31.camel@tglx.tec.linutronix.de> <1134772964.2806.50.camel@tglx.tec.linutronix.de> <20051217002929.GA7151@tsunami.ccur.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 984 Lines: 18 On Fri, Dec 16, 2005 at 11:34:03PM -0800, Linus Torvalds wrote: > I really can't think of any blocking kernel lock where priority > inheritance would make _any_ sense at all. Please give me an example. I have a better example of something we currently get wrong that I haven't heard any RT person worry about yet. If two tasks are sleeping on the same semaphore, the one to be woken up will be the first one to wait for it, not the highest-priority task. Obviously, this was introduced by the wake-one semantics. But how to fix it? Should we scan the entire queue looking for the best task to wake? Should we try to maintain the wait list in priority order? Or should we just not care? Should we document that we don't care? ;-) - 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/