From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCHSET] percpu: generalize first chunk allocators and improve lpage NUMA support Date: Thu, 25 Jun 2009 02:02:02 +0200 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 Return-path: 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 Content-Disposition: inline In-Reply-To: <20090624165508.30b88343.akpm@linux-foundation.org> Sender: linux-arch-owner@vger.kernel.org List-ID: 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 > 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.