From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267675AbUHEN1a (ORCPT ); Thu, 5 Aug 2004 09:27:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267677AbUHEN1J (ORCPT ); Thu, 5 Aug 2004 09:27:09 -0400 Received: from zcars04e.nortelnetworks.com ([47.129.242.56]:9719 "EHLO zcars04e.nortelnetworks.com") by vger.kernel.org with ESMTP id S267675AbUHEN0u (ORCPT ); Thu, 5 Aug 2004 09:26:50 -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> From: Linh Dang Organization: Null Date: Thu, 05 Aug 2004 09:26:45 -0400 In-Reply-To: <4111E3B5.1070608@redhat.com> (Ulrich Drepper's message of "Thu, 05 Aug 2004 00:37:25 -0700") 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 Ulrich Drepper wrote: > The fast path for all locking primitives etc in nptl today is > entirely at userlevel. Normally just a single atomic operation with > a dozen other instructions. With the fusyn stuff each and every > locking operation needs a system call to register/unregister the > thread as it locks/unlocks mutex/rwlocks/etc. Go figure how well > this works. We are talking about making the fast path of the > locking primitives two/three/four orders of magnitude more > expensive. And this for absolutely no benefit for 99.999% of all > the code which uses threads. > Is there an EFFICIENT way to add priority-inheritance to futex? the lack of priority-inheritance is biggest headache for RT applications running on top of NPTL/kernel-2.6. And there's is a LOT more of us (RT users who want to use NPTL/kernel-2.6) than you might think. I guess we're just not vocal. -- Linh Dang