From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755069AbZCDATS (ORCPT ); Tue, 3 Mar 2009 19:19:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751127AbZCDATE (ORCPT ); Tue, 3 Mar 2009 19:19:04 -0500 Received: from terminus.zytor.com ([198.137.202.10]:44106 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751084AbZCDATD (ORCPT ); Tue, 3 Mar 2009 19:19:03 -0500 Message-ID: <49ADC80F.6010200@zytor.com> Date: Tue, 03 Mar 2009 16:15:11 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Rusty Russell CC: Tejun Heo , Ingo Molnar , tglx@linutronix.de, x86@kernel.org, linux-kernel@vger.kernel.org, jeremy@goop.org, cpw@sgi.com, nickpiggin@yahoo.com.au, ink@jurassic.park.msu.ru Subject: Re: [PATCHSET x86/core/percpu] improve the first percpu chunk allocation References: <1235445101-7882-1-git-send-email-tj@kernel.org> <20090224141217.GA17287@elte.hu> <49A40624.4000100@kernel.org> <200903041033.09502.rusty@rustcorp.com.au> In-Reply-To: <200903041033.09502.rusty@rustcorp.com.au> 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 Rusty Russell wrote: > On Wednesday 25 February 2009 01:07:24 Tejun Heo wrote: >> it always >> saves a 2MB TLB entry for all the non-NUMA machines out there. > > Note that everyone keeps talking about "a" TLB entry; I wanted to make > sure (esp. for those of us reading from the sidelines), it's not: it's > up to num_possible_cpus() TLB entries. Of course, many paths won't access > other CPU's data, but it'd be interesting (and pretty easy) to actually > instrument how rare this is... > Actually it's up to the number of actual CPUs in the system... obviously there isn't any data allocated for non-present CPUs. -hpa