From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261415AbVFNXUs (ORCPT ); Tue, 14 Jun 2005 19:20:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261411AbVFNXUZ (ORCPT ); Tue, 14 Jun 2005 19:20:25 -0400 Received: from mail.suse.de ([195.135.220.2]:11656 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S261416AbVFNXTM (ORCPT ); Tue, 14 Jun 2005 19:19:12 -0400 Date: Wed, 15 Jun 2005 01:19:11 +0200 From: Andi Kleen To: Christoph Lameter Cc: Andi Kleen , christoph , akpm@osdl.org, linux-kernel@vger.kernel.org, shai@scalex86.org Subject: Re: [PATCH] Move some variables into the "most_readonly" section?? Message-ID: <20050614231911.GV11898@wotan.suse.de> References: <20050608131839.GP23831@wotan.suse.de> <20050614230411.GU11898@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 14, 2005 at 04:17:14PM -0700, Christoph Lameter wrote: > On Wed, 15 Jun 2005, Andi Kleen wrote: > > > > Hmm. No. The bigger cpu maps may benefit from cacheline alignment for > > > even for read access. > > > > Why? Can you please explain that. It doesn't make sense to me. > > Its more likely to get a big piece of the array in a single > cacheline if the array starts at the beginning of a cacheline. > > If these maps would start in the middle of a cacheline then additional > cacheline fetches may become necessary to scan an array etc. But the CPUs do prefetching anyways for that. Do you have numbers that this is actually worth it? -Andi