Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266768AbUJTGHf (ORCPT ); Wed, 20 Oct 2004 02:07:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266034AbUJTGEn (ORCPT ); Wed, 20 Oct 2004 02:04:43 -0400 Received: from [64.167.48.9] ([64.167.48.9]:45074 "EHLO mail.bigsurwireless.com") by vger.kernel.org with ESMTP id S266768AbUJTF6g convert rfc822-to-8bit (ORCPT ); Wed, 20 Oct 2004 01:58:36 -0400 From: John Alvord To: Lee Revell Cc: Ryan Anderson , "Jeff V. Merkey" , Dax Kelson , Linus Torvalds , Kernel Mailing List Subject: Re: Linux v2.6.9 and GPL Buyout Date: Tue, 19 Oct 2004 22:58:26 -0700 Message-ID: References: <417550FB.8020404@drdos.com> <1098218286.8675.82.camel@mentorng.gurulabs.com> <41757478.4090402@drdos.com> <20041020034524.GD10638@michonline.com> <1098245904.23628.84.camel@krustophenia.net> In-Reply-To: <1098245904.23628.84.camel@krustophenia.net> X-Mailer: Forte Agent 2.0/32.652 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1262 Lines: 26 On Wed, 20 Oct 2004 00:18:25 -0400, Lee Revell wrote: >On Tue, 2004-10-19 at 23:45, Ryan Anderson wrote: >> RCU - originally a paper, implemented in Dynix and in other operating >> systems from the paper (and patent), implemented in Linux as well. > >You could also make a strong argument that that patent is invalid >because RCU is obvious. I was doing this with perl and SQL before I >ever heard of RCU. If you don't want to lock a table (or didn't realize >SQL had such a thing as table locking :-) you just fetch a value, make >some calculation on it, then do the update iff that value has not >changed. If it has changed you fetch the new value and go back to step >1. It's just the obvious way to update a shared data structure if you >have cmpxchg but no locking. 1972, IBM S/370 instruction set, CS Compare and Swap (32 bits) and CDS Compare Double and Swap (64 bits), atomic compare and replace if test equal. The Principles of Operation book even had sample code... john alvord - 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/