From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932407AbVLMDYk (ORCPT ); Mon, 12 Dec 2005 22:24:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932405AbVLMDYk (ORCPT ); Mon, 12 Dec 2005 22:24:40 -0500 Received: from ms-smtp-03.nyroc.rr.com ([24.24.2.57]:36513 "EHLO ms-smtp-03.nyroc.rr.com") by vger.kernel.org with ESMTP id S932402AbVLMDYj (ORCPT ); Mon, 12 Dec 2005 22:24:39 -0500 Subject: Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation From: Steven Rostedt To: Daniel Walker Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, matthew@wil.cx, arjan@infradead.org, hch@infradead.org, akpm@osdl.org, torvalds@osdl.org, David Howells , Ingo Molnar In-Reply-To: <1134435458.22269.11.camel@localhost.localdomain> References: <1134435458.22269.11.camel@localhost.localdomain> Content-Type: text/plain Date: Mon, 12 Dec 2005 22:23:48 -0500 Message-Id: <1134444228.24145.25.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2005-12-12 at 16:57 -0800, Daniel Walker wrote: > On Mon, 2005-12-12 at 23:45 +0000, David Howells wrote: > > > (1) Provides a simple xchg() based semaphore as a default for all > > architectures that don't wish to override it and provide their own. > > > > Overriding is possible by setting CONFIG_ARCH_IMPLEMENTS_MUTEX and > > supplying asm/mutex.h > > > > Partial overriding is possible by #defining mutex_grab(), mutex_release() > > and is_mutex_locked() to perform the appropriate optimised functions. > > Your code is really similar to the RT mutex, which does everything that > your mutex does at least ? Assuming you've reviewed the RT mutex, why > would we want to use yours over it? Maybe this would be the better !PREEMPT_RT version. But the true mutex that Ingo is making would be used for the PREEMPT_RT side. This code at least brings down the over head of semaphores where they are not really needed. Looking at the code slightly (I must admit, I spent maybe 30 seconds looking at it), it does seem a little similar to Ingo's. Could just be coincidence, since the methods are pretty much what multiple people would come up with. But you both work for RedHat, hmm. -- Steve