From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750838AbWFXPw1 (ORCPT ); Sat, 24 Jun 2006 11:52:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750846AbWFXPw1 (ORCPT ); Sat, 24 Jun 2006 11:52:27 -0400 Received: from main.gmane.org ([80.91.229.2]:38843 "EHLO ciao.gmane.org") by vger.kernel.org with ESMTP id S1750838AbWFXPw0 (ORCPT ); Sat, 24 Jun 2006 11:52:26 -0400 X-Injected-Via-Gmane: http://gmane.org/ To: linux-kernel@vger.kernel.org From: Joe Seigh Subject: Re: Userspace RCU+rtth hack (was Re: [patch 3/3] radix-tree: RCU lockless readside) Date: Sat, 24 Jun 2006 11:55:29 -0400 Message-ID: References: <20060408134635.22479.79269.sendpatchset@linux.site> <20060408134707.22479.33814.sendpatchset@linux.site> <20060622014949.GA2202@us.ibm.com> <20060622154518.GA23109@wotan.suse.de> <20060622163032.GC1295@us.ibm.com> <20060622165551.GB23109@wotan.suse.de> <20060622174057.GF1295@us.ibm.com> <20060622182343.GA29003@wotan.suse.de> <20060622202552.GH1295@us.ibm.com> <20060624102024.GA27865@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@sea.gmane.org X-Gmane-NNTP-Posting-Host: c-24-60-56-212.hsd1.ma.comcast.net User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) X-Accept-Language: en-us, en In-Reply-To: <20060624102024.GA27865@wotan.suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Nick Piggin wrote: > On Thu, Jun 22, 2006 at 01:25:53PM -0700, Paul E. McKenney wrote: > > >>I have a few user-mode implementations myself, but the lawyers won't >>let me release them. :-( > > > I imagine they're quite a bit faster than my quick hack, too ;) > > I did a number of implementations trying out a number of different strategies. Yes, they're quite a bit faster and scale better than lock based solutions in most cases. They used to be on my atomic-ptr-plus sourceforge project page. The issue is patents I think. The RCU patents aren't in any patent pools for use by open source. The only thing I think you can do is apply for what are known as blocking patents for any improvements on RCU. But you'd have to sell the patent to recover your patent costs and who would have money for that do you think, the EFF or a patent troll? I'm guessing that if lock-free synchronization comes to userspace it will be in the form of a licensed library that you have to pay for. There's two out there already based on Maged Michael's hazard pointers. One from Intel here http://www.intel.com/cd/software/products/asmo-na/eng/272688.htm and one from here http://www.pss-ab.com/ -- Joe Seigh