From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755722AbZF3TPo (ORCPT ); Tue, 30 Jun 2009 15:15:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752959AbZF3TPh (ORCPT ); Tue, 30 Jun 2009 15:15:37 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:59214 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752342AbZF3TPg (ORCPT ); Tue, 30 Jun 2009 15:15:36 -0400 Date: Tue, 30 Jun 2009 21:15:17 +0200 From: Ingo Molnar To: Andrew Morton Cc: Christoph Lameter , tj@kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-arch@vger.kernel.org, andi@firstfloor.org, hpa@zytor.com, tglx@linutronix.de Subject: Re: [PATCHSET] percpu: generalize first chunk allocators and improve lpage NUMA support Message-ID: <20090630191517.GB20567@elte.hu> References: <1245850216-31653-1-git-send-email-tj@kernel.org> <20090624165508.30b88343.akpm@linux-foundation.org> <20090629163937.94c8cedd.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090629163937.94c8cedd.akpm@linux-foundation.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andrew Morton wrote: > On Mon, 29 Jun 2009 19:20:53 -0400 (EDT) > Christoph Lameter wrote: > > > On Wed, 24 Jun 2009, Andrew Morton wrote: > > > > > I assume from the tremendous number of > > > for_each_possible_cpu()s that CPU hotplug awareness won't be > > > happening. > > > > Per cpu areas are allocated for all possible processors. No need > > to handle offlining and onlining them. > > Well yes. My point is that this is a bug-not-a-feature ;) Yeah, it's a bug for something like a virtual environment which boots generic kernels that might have 64 possible CPUs (on a true 64-way system), but which will have fewer in practice. It's pretty basic stuff: the on-demand allocation of percpu resources. Ingo