Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932592AbVLQUMU (ORCPT ); Sat, 17 Dec 2005 15:12:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932507AbVLQUMU (ORCPT ); Sat, 17 Dec 2005 15:12:20 -0500 Received: from smtp.osdl.org ([65.172.181.4]:20183 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S932180AbVLQUMT (ORCPT ); Sat, 17 Dec 2005 15:12:19 -0500 Date: Sat, 17 Dec 2005 12:11:39 -0800 (PST) From: Linus Torvalds To: David Howells cc: Steven Rostedt , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, akpm@osdl.org Subject: Re: [PATCH 1/12]: MUTEX: Implement mutexes In-Reply-To: <14917.1134847311@warthog.cambridge.redhat.com> Message-ID: References: <200512162313.jBGND7g4019623@warthog.cambridge.redhat.com> <1134791914.13138.167.camel@localhost.localdomain> <14917.1134847311@warthog.cambridge.redhat.com> 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 Content-Length: 1487 Lines: 39 On Sat, 17 Dec 2005, David Howells wrote: > > Linux supports a number of those archs. Amongst them are 68000 (TAS), arm (SWP > I think), i386 (XCHG), and FRV (SWAP). I'm also looking at another that only > has BSET/BCLR. Don't bother putting i386 in that list. Quite frankly, you've done it before, and I think it's intellectually totally dishonest. i386 does semaphores with a "lock decl". You CANNOT DO IT FASTER. I dare you. Why the hell do you try to make it sound as if x86 would need this new thing, when it absolutely does NOT need it. Yes, x86 _also_ has an xchg instruction, but hey, that's a total non-argument. We don't actually use that. Of the other architectures you list, only ARM is really important. And no, arm doesn't do swap. It does LL/SC (except they call it "ldrex/strex", which I assume stands for "load/store with reservation and X just because X is cool. Yeah, we're cool" (*)). 68k is dead. Nobody cares. So just say it outright: this is totally just a FRV feature, and NOBODY ELSE IS IN THE LEAST INTERESTED. Ok? Just to inject a little honesty here. Linus (*) Actually, some arm docs I found implies that "ex" stands for "exclusive", but that leaves me wondering what the "r" stands for? - 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/