Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756324AbYGJVFu (ORCPT ); Thu, 10 Jul 2008 17:05:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754053AbYGJVFm (ORCPT ); Thu, 10 Jul 2008 17:05:42 -0400 Received: from terminus.zytor.com ([198.137.202.10]:59809 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753536AbYGJVFm (ORCPT ); Thu, 10 Jul 2008 17:05:42 -0400 Message-ID: <48767804.8080007@zytor.com> Date: Thu, 10 Jul 2008 16:58:44 -0400 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Christoph Lameter CC: Mike Travis , Jeremy Fitzhardinge , "Eric W. Biederman" , Arjan van de Ven , Ingo Molnar , Andrew Morton , Jack Steiner , linux-kernel@vger.kernel.org, Rusty Russell 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> <20080709133958.612635f0@infradead.org> <4875231F.1020506@zytor.com> <487524A0.6020304@goop.org> <487529AE.3060505@zytor.com> <48753A71.2030006@zytor.com> <48763732.7020805@sgi.com> <487641D6.5060206@goop.org> <487649B2.3000405@sgi.com> <48764E8A.5010400@zytor.com> <4876766F.4030605@linux-foundation.org> In-Reply-To: <4876766F.4030605@linux-foundation.org> 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: 734 Lines: 16 Christoph Lameter wrote: > H. Peter Anvin wrote: > >> I'm much more concerned about wasting an average of 1 MB of memory per CPU. > > Well all the memory that is now allocated via allocpercpu()s will be allocated from that 2MB segment. And cpu_alloc packs variables in a dense way. The current slab allocations try to avoid sharing cachelines which wastes lots of memory for every allocation for each and every processor. > And how much is that, especially on *small* systems? -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/