Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758227AbZFYACT (ORCPT ); Wed, 24 Jun 2009 20:02:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755091AbZFYACF (ORCPT ); Wed, 24 Jun 2009 20:02:05 -0400 Received: from one.firstfloor.org ([213.235.205.2]:34115 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755138AbZFYACE (ORCPT ); Wed, 24 Jun 2009 20:02:04 -0400 Date: Thu, 25 Jun 2009 02:02:02 +0200 From: Andi Kleen To: Andrew Morton Cc: Tejun Heo , linux-kernel@vger.kernel.org, x86@kernel.org, linux-arch@vger.kernel.org, mingo@elte.hu, andi@firstfloor.org, hpa@zytor.com, tglx@linutronix.de, cl@linux-foundation.org Subject: Re: [PATCHSET] percpu: generalize first chunk allocators and improve lpage NUMA support Message-ID: <20090625000202.GR6760@one.firstfloor.org> References: <1245850216-31653-1-git-send-email-tj@kernel.org> <20090624165508.30b88343.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090624165508.30b88343.akpm@linux-foundation.org> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 810 Lines: 26 > I assume from the tremendous number of for_each_possible_cpu()s that > CPU hotplug awareness won't be happening. > > Do we have a feeling for the amount of wastage here? If > > num_possible_cpus() - num_online_cpus() == N Haven't read the new patches, but per cpu data always was sized for all possible CPUs. > and N is large, what did it cost? > And what are reasonable values of N? N should normally not be large anymore, since num_possible_cpus() is sized based on firmware information now. -Andi -- ak@linux.intel.com -- Speaking for myself only. -- 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/