From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964970AbWDHOm2 (ORCPT ); Sat, 8 Apr 2006 10:42:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964971AbWDHOm2 (ORCPT ); Sat, 8 Apr 2006 10:42:28 -0400 Received: from [4.79.56.4] ([4.79.56.4]:50064 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id S964970AbWDHOm2 (ORCPT ); Sat, 8 Apr 2006 10:42:28 -0400 Subject: Re: [PATCH] Kconfig.debug: Set DEBUG_MUTEX to off by default From: Arjan van de Ven To: tim.c.chen@linux.intel.com Cc: linux-kernel@vger.kernel.org In-Reply-To: <1144429008.25886.17.camel@localhost.localdomain> References: <1144429008.25886.17.camel@localhost.localdomain> Content-Type: text/plain Date: Sat, 08 Apr 2006 16:42:27 +0200 Message-Id: <1144507347.2989.2.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2006-04-07 at 09:56 -0700, Tim Chen wrote: > Hi, > > DEBUG_MUTEX flag is on by default in current kernel configuration. > > During performance testing, we saw mutex debug functions like > mutex_debug_check_no_locks_freed (called by kfree()) is expensive as it > goes through a global list of memory areas with mutex lock and do the > checking. For benchmarks such as Volanomark and Hackbench, we have seen > more than 40% drop in performance on some platforms. We suggest to set > DEBUG_MUTEX off by default. Or at least do that later when we feel that > the mutex changes in the current code have stabilized. > > Tim Chen > > Signed-off-by: Tim Chen > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -101,7 +101,7 @@ config DEBUG_PREEMPT > > config DEBUG_MUTEXES > bool "Mutex debugging, deadlock detection" > - default y > + default n don't do default n, just remove the line instead ;)