From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757529AbYJIGtW (ORCPT ); Thu, 9 Oct 2008 02:49:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751406AbYJIGtP (ORCPT ); Thu, 9 Oct 2008 02:49:15 -0400 Received: from one.firstfloor.org ([213.235.205.2]:50714 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751187AbYJIGtO (ORCPT ); Thu, 9 Oct 2008 02:49:14 -0400 Date: Thu, 9 Oct 2008 08:55:29 +0200 From: Andi Kleen To: Lai Jiangshan Cc: paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, mingo@elte.hu, rjw@sisk.pl, dipankar@in.ibm.com, tglx@linuxtronix.de, andi@firstfloor.org Subject: Re: [PATCH] rudimentary tracing for Classic RCU Message-ID: <20081009065529.GC24560@one.firstfloor.org> References: <20081006232837.GA1157@basil.nowhere.org> <20081007030822.GC6820@linux.vnet.ibm.com> <20081007071544.GC20740@one.firstfloor.org> <20081007152629.GH6384@linux.vnet.ibm.com> <20081007154939.GN20740@one.firstfloor.org> <20081007163401.GJ6384@linux.vnet.ibm.com> <20081007210947.GP20740@one.firstfloor.org> <20081007212215.GN6384@linux.vnet.ibm.com> <20081009010846.GA10188@linux.vnet.ibm.com> <48EDA2A6.9070707@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48EDA2A6.9070707@cn.fujitsu.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > In this case, why not define it as: > static char buf[20*NR_CPUS + 100]; Actually you should near never use NR_CPUS now but always num_possible_cpus() (or even num_online_cpus()) Using NR_CPUS can lead to extreme waste of memory on kernels which are compiled for 4096 CPUs for example. And with num_possible_cpus() kmalloc is needed. -Andi