From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752596AbXCXPzK (ORCPT ); Sat, 24 Mar 2007 11:55:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752827AbXCXPzK (ORCPT ); Sat, 24 Mar 2007 11:55:10 -0400 Received: from mail.clusterfs.com ([206.168.112.78]:55495 "EHLO mail.clusterfs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752596AbXCXPzI (ORCPT ); Sat, 24 Mar 2007 11:55:08 -0400 From: Nikita Danilov MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17925.18904.820106.145029@gargle.gargle.HOWL> Date: Sat, 24 Mar 2007 18:55:04 +0300 To: Nick Piggin Cc: Ingo Molnar , Linux Kernel Mailing List , Ravikiran G Thirumalai Subject: Re: [rfc][patch] queued spinlocks (i386) Newsgroups: gmane.linux.kernel In-Reply-To: <20070323103243.GE11577@wotan.suse.de> References: <20070323085910.GA11577@wotan.suse.de> <20070323100418.GA30740@elte.hu> <20070323103243.GE11577@wotan.suse.de> X-Mailer: VM 7.17 under 21.5 (patch 17) "chayote" (+CVS-20040321) XEmacs Lucid X-SystemSpamProbe: GOOD 0.0000621 8c11c36c52d7cd313eb66bc9ceeb27e9 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Nick Piggin writes: > On Fri, Mar 23, 2007 at 11:04:18AM +0100, Ingo Molnar wrote: > > > > * Nick Piggin wrote: > > > > > Implement queued spinlocks for i386. [...] > > > > isnt this patented by MS? (which might not worry you SuSE/Novell guys, > > but it might be a worry for the rest of the world ;-) > > Hmm, it looks like they have implemented a system where the spinning > cpu sleeps on a per-CPU variable rather than the lock itself, and > the releasing cpu writes to that variable to wake it. They do this > so that spinners don't continually perform exclusive->shared > transitions on the lock cacheline. They call these things queued > spinlocks. They don't seem to be very patent worthy either, but Indeed, this technique is very well known. E.g., http://citeseer.ist.psu.edu/anderson01sharedmemory.html has a whole section (3. Local-spin Algorithms) on them, citing papers from the 1990 onward. Nikita.