From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759248AbXGISMo (ORCPT ); Mon, 9 Jul 2007 14:12:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754328AbXGISMh (ORCPT ); Mon, 9 Jul 2007 14:12:37 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:58062 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753600AbXGISMh (ORCPT ); Mon, 9 Jul 2007 14:12:37 -0400 Date: Mon, 9 Jul 2007 11:11:36 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Martin Bligh cc: Andi Kleen , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [patch 00/10] [RFC] SLUB patches for more functionality, performance and maintenance In-Reply-To: <46925B5D.8000507@google.com> Message-ID: References: <20070708034952.022985379@sgi.com> <46925B5D.8000507@google.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 On Mon, 9 Jul 2007, Martin Bligh wrote: > Those numbers came from Mathieu Desnoyers (LTTng) if you > want more details. Okay the source for these numbers is in his paper for the OLS 2006: Volume 1 page 208-209? I do not see the exact number that you referred to there. He seems to be comparing spinlock acquire / release vs. cmpxchg. So I guess you got your material from somewhere else? Also the cmpxchg used there is the lockless variant. cmpxchg 29 cycles w/o lock prefix and 112 with lock prefix. I see you reference another paper by Desnoyers: http://tree.celinuxforum.org/CelfPubWiki/ELC2006Presentations?action=AttachFile&do=get&target=celf2006-desnoyers.pdf I do not see anything relevant there. Where did those numbers come from? The lockless cmpxchg is certainly an interesting idea. Certain for some platforms I could disable preempt and then do a lockless cmpxchg.