From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266773AbUGLNxs (ORCPT ); Mon, 12 Jul 2004 09:53:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266185AbUGLNwy (ORCPT ); Mon, 12 Jul 2004 09:52:54 -0400 Received: from ozlabs.org ([203.10.76.45]:58055 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S266182AbUGLNwu (ORCPT ); Mon, 12 Jul 2004 09:52:50 -0400 Date: Mon, 12 Jul 2004 18:39:30 +1000 From: Anton Blanchard To: Shai Fultheim Cc: "'Andrew Morton'" , "'Linux Kernel ML'" Subject: Re: [PATCH] Alignment for CPU maps, add padding semantics Message-ID: <20040712083930.GA2324@krispykreme> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.6+20040523i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, > The attached patch add missing alignments for CPU maps (cpu_online_map, > node_2_cpu_mask, cpu_2_node, cpu_2_logical_apicid). It allows better > cache-line utilization by having the most usable part of each map on > same cache-line. These bitmaps are pretty much readonly and 4 bytes on most machines and this change makes them up to 128 bytes long. They are also naturally aligned in the 4 byte case so cannot cross a cacheline boundary. It makes much more sense to have all these readonly structures packed together in the same cacheline. Anton