Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754953AbZGARdx (ORCPT ); Wed, 1 Jul 2009 13:33:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754380AbZGARde (ORCPT ); Wed, 1 Jul 2009 13:33:34 -0400 Received: from smtp3.ultrahosting.com ([74.213.175.254]:59336 "EHLO smtp.ultrahosting.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754032AbZGARdd (ORCPT ); Wed, 1 Jul 2009 13:33:33 -0400 Date: Wed, 1 Jul 2009 13:33:03 -0400 (EDT) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Andi Kleen cc: Tejun Heo , Ingo Molnar , Andrew Morton , linux-kernel@vger.kernel.org, x86@kernel.org, linux-arch@vger.kernel.org, hpa@zytor.com, tglx@linutronix.de Subject: Re: [PATCHSET] percpu: generalize first chunk allocators and improve lpage NUMA support In-Reply-To: <20090701131146.GR6760@one.firstfloor.org> Message-ID: References: <20090629163937.94c8cedd.akpm@linux-foundation.org> <20090630191517.GB20567@elte.hu> <20090630213146.GA17492@elte.hu> <4A4A9DC6.6020003@kernel.org> <20090701064250.GM6760@one.firstfloor.org> <4A4B38C5.1070504@kernel.org> <20090701122312.GP6760@one.firstfloor.org> <4A4B5C32.1010009@kernel.org> <20090701131146.GR6760@one.firstfloor.org> 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: 879 Lines: 18 On Wed, 1 Jul 2009, Andi Kleen wrote: > And it's imho unclear if that is all worth it just to avoid > wasting some memory in the "256 possible CPUs" case (which > I doubt is particularly realistic anyways, at least I don't > know of any Hypervisor today that scales to 256 CPUs) I basically agree. Its not worth it given the rare cases where this matters. It will be a lot of code with callbacks in each subsystem. One of the motivations of working on revising the percpu handling for me was that we could get rid of these screwy callbacks that are rarely tested and cause all sorts of other issues with locking and serialization. -- 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/