From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750891Ab1GOLXQ (ORCPT ); Fri, 15 Jul 2011 07:23:16 -0400 Received: from anchor-post-3.mail.demon.net ([195.173.77.134]:51467 "EHLO anchor-post-3.mail.demon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750745Ab1GOLXP (ORCPT ); Fri, 15 Jul 2011 07:23:15 -0400 Subject: Re: [PATCH] sched: reorder root_domain to remove 64 bit alignment padding From: Richard Kennedy To: Peter Zijlstra Cc: Ingo Molnar , lkml Date: Fri, 15 Jul 2011 12:23:14 +0100 In-Reply-To: <1310726660.2586.313.camel@twins> References: <1310726492.1977.5.camel@castor.rsk> <1310726660.2586.313.camel@twins> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.0.2 (3.0.2-3.fc15) Content-Transfer-Encoding: 7bit Message-ID: <1310728994.1977.15.camel@castor.rsk> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2011-07-15 at 12:44 +0200, Peter Zijlstra wrote: > On Fri, 2011-07-15 at 11:41 +0100, Richard Kennedy wrote: > > Reorder root_domain to remove 8 bytes of alignment padding on 64 bit > > builds, this shrinks the size from 1736 to 1728 bytes, therefore using > > one fewer cachelines. > > depends a bit on how insane struct cpupri is, but yeah, good compaction. > Thanks! Thanks Peter, argh -- I hadn't spotted that cpupri used NR_CPUS and was so variable in size. I guess there won't be much benefit then, as the distros seem to always set NR_CPUS to some insanely huge value ;) regards Richard