From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267205AbUHENXP (ORCPT ); Thu, 5 Aug 2004 09:23:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267670AbUHENXO (ORCPT ); Thu, 5 Aug 2004 09:23:14 -0400 Received: from zcars04e.nortelnetworks.com ([47.129.242.56]:4599 "EHLO zcars04e.nortelnetworks.com") by vger.kernel.org with ESMTP id S267205AbUHENXJ (ORCPT ); Thu, 5 Aug 2004 09:23:09 -0400 To: linux-kernel@vger.kernel.org Subject: Re: [RFC/PATCH] FUSYN Realtime & robust mutexes for Linux, v2.3.1 References: <20040804232123.3906dab6.akpm@osdl.org> <4111DC8C.7050504@redhat.com> <20040805001737.78afb0d6.akpm@osdl.org> <4111E3B5.1070608@redhat.com> <1091704539.5031.42.camel@bach> From: Linh Dang Organization: Null Date: Thu, 05 Aug 2004 09:23:06 -0400 In-Reply-To: <1091704539.5031.42.camel@bach> (Rusty Russell's message of "Thu, 05 Aug 2004 21:48:05 +1000") Message-ID: User-Agent: Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (gnu/linux) 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 Rusty Russell wrote: > I don't think this is neccessarily true: I think that platforms with > 64-bit compare-and-exchange can do the whole thing in userspace. > They would set the mutex and stamp in the thread ID simultanously, > allowing for "dead thread" detection (ie. I didn't get the lock, and > it's a robust mutex: check the holder is still alive). Or for priority-inheritance: try get the lock, if failed raised the holder's priority to mine if necessary. > > W/o 64-bit compare-and-exchange a 100% robust solution may not be > possible though. PPC arch can do a lot of things in a pseudo-atomic way. > > Thoughts? > Rusty. -- Linh Dang