Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759757AbZF3W4q (ORCPT ); Tue, 30 Jun 2009 18:56:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759465AbZF3W4N (ORCPT ); Tue, 30 Jun 2009 18:56:13 -0400 Received: from smtp3.ultrahosting.com ([74.213.175.254]:46181 "EHLO smtp.ultrahosting.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1759410AbZF3W4J (ORCPT ); Tue, 30 Jun 2009 18:56:09 -0400 Date: Tue, 30 Jun 2009 18:55:55 -0400 (EDT) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Ingo Molnar 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 In-Reply-To: <20090630223138.GH1241@elte.hu> Message-ID: 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> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 997 Lines: 24 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. > How would you allow that guest to stay on 2 virtual CPUs but still > be able to hot-plug many other CPUs if the guest context rises above > its original CPU utilization? The use case is a guest that needs to add a couple of thousand processors? That will require lots of memory and special configuration of the guest environment simulated. Yes that is an extreme case that will require lots of per cpu memory. -- 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/