Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757968AbZF3XIK (ORCPT ); Tue, 30 Jun 2009 19:08:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753300AbZF3XH5 (ORCPT ); Tue, 30 Jun 2009 19:07:57 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:51552 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752670AbZF3XH4 (ORCPT ); Tue, 30 Jun 2009 19:07:56 -0400 Date: Wed, 1 Jul 2009 01:07:43 +0200 From: Ingo Molnar To: Christoph Lameter Cc: Andrew Morton , 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: <20090630230743.GA17968@elte.hu> References: <1245850216-31653-1-git-send-email-tj@kernel.org> <20090624165508.30b88343.akpm@linux-foundation.org> <20090629163937.94c8cedd.akpm@linux-foundation.org> <20090630191517.GB20567@elte.hu> <20090630213146.GA17492@elte.hu> <20090630223138.GH1241@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Content-Length: 990 Lines: 28 * Christoph Lameter wrote: > On Wed, 1 Jul 2009, Ingo Molnar wrote: > > > The usecase i'm talking about is to boot a generic, > > many-CPUs-capable kernel in a guest image. > > The many-cpu-capable kernel is not the issue. The number of > potential cpus is config information provided by the hardware. In > your case the host system provides the number of possible > processors. Say it says "256 CPUs". But i only run a 2 CPU guest system. But i want to run it with the _on demand capability_ to scale up to 256 virtual CPUs if needed, without having to reboot the guest and without having to allocate all the percpu space for 256 CPUs beforehand. Ok? It is a simple, basic OS feature and concept. Ingo -- 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/