Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759646AbYGJTjv (ORCPT ); Thu, 10 Jul 2008 15:39:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753222AbYGJTjn (ORCPT ); Thu, 10 Jul 2008 15:39:43 -0400 Received: from terminus.zytor.com ([198.137.202.10]:51300 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753206AbYGJTjm (ORCPT ); Thu, 10 Jul 2008 15:39:42 -0400 Message-ID: <487663C4.6040309@zytor.com> Date: Thu, 10 Jul 2008 15:32:20 -0400 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Mike Travis CC: "Eric W. Biederman" , Christoph Lameter , Jeremy Fitzhardinge , Ingo Molnar , Andrew Morton , Jack Steiner , linux-kernel@vger.kernel.org, Arjan van de Ven Subject: Re: [RFC 00/15] x86_64: Optimize percpu accesses References: <20080709165129.292635000@polaris-admin.engr.sgi.com> <20080709200757.GD14009@elte.hu> <48751B57.8030605@goop.org> <48751CF9.4020901@linux-foundation.org> <4875209D.8010603@goop.org> <48752CCD.30507@linux-foundation.org> <48753C99.5050408@goop.org> <487555A8.2050007@zytor.com> <487556A5.5090907@goop.org> <4876194E.4080205@linux-foundation.org> <48761C06.3020003@zytor.com> <48762A3B.5050104@linux-foundation.org> <48762DD2.5090802@zytor.com> <487637A1.4080403@linux-foundation.org> <48764C21.4020601@zytor.com> <4876608B.10408@sgi.com> In-Reply-To: <4876608B.10408@sgi.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 711 Lines: 18 Mike Travis wrote: > > The biggest growth came from moving all the xxx[NR_CPUS] arrays into > the per cpu area. So you free up a huge amount of unused memory when > the NR_CPUS count starts getting into the ozone layer. 4k now, 16k > real soon now, ??? future? > Even (or perhaps especially) so, allocating the percpu area in 2 MB increments is a total nonstarter. It hurts the small, common configurations way too much. For SGI, it's probably fine. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/