From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265939AbUBKQs6 (ORCPT ); Wed, 11 Feb 2004 11:48:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265941AbUBKQs6 (ORCPT ); Wed, 11 Feb 2004 11:48:58 -0500 Received: from dictum-ext.geekmail.cc ([204.239.179.245]:20958 "EHLO mailer01.geekmail.cc") by vger.kernel.org with ESMTP id S265939AbUBKQsz (ORCPT ); Wed, 11 Feb 2004 11:48:55 -0500 Message-ID: <402A5CEC.2030603@swapped.cc> Date: Wed, 11 Feb 2004 08:48:44 -0800 From: Alex Pankratov User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6b) Gecko/20031205 Thunderbird/0.4 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Andi Kleen CC: linux-kernel@vger.kernel.org Subject: Re: [PATCH] [2.6] [2/2] hlist: remove IFs from hlist functions References: <4029CB7E.4030003@swapped.cc.suse.lists.linux.kernel> <4029CF24.1070307@osdl.org.suse.lists.linux.kernel> <4029D2D5.7070504@swapped.cc.suse.lists.linux.kernel> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen wrote: > Alex Pankratov writes: > >> >>No, because its 'pprev' field *is* getting modified. > > I didn't notice this before, sorry. But this could end up > being a scalability problem on big SMP systems. Even though > the cache line of this is never read it will bounce all the > time between all CPUs using hlists and add considerably > latency and cross node traffic. Remember Linux is supposed > to run well on 128 CPU machines now. That's a bit above my head. How does this potential latency compare to the speed up due to not having CMPs ? My cycle counting skills are a bit dusty :) > > Maybe you can make it UP only, but I'm still not sure it's > worth it. > Sorry, I didn't the 'UP' part.