From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756830AbYA0LGT (ORCPT ); Sun, 27 Jan 2008 06:06:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751006AbYA0LGJ (ORCPT ); Sun, 27 Jan 2008 06:06:09 -0500 Received: from e34.co.us.ibm.com ([32.97.110.152]:56990 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751115AbYA0LGI (ORCPT ); Sun, 27 Jan 2008 06:06:08 -0500 Date: Sun, 27 Jan 2008 03:05:59 -0800 From: "Paul E. McKenney" To: Stefan Richter Cc: Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: preemptible RCU bug (was Re: [git pull] scheduler changes for v2.6.25) Message-ID: <20080127110559.GB28315@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20080125203740.GA31784@elte.hu> <479B87B9.8080005@s5r6.in-berlin.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <479B87B9.8080005@s5r6.in-berlin.de> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 26, 2008 at 08:19:21PM +0100, Stefan Richter wrote: > Ingo Molnar wrote: > > - Paul E. McKenney's preemptible RCU code. > > BUG: New Kconfig option without help text. > > $ make oldconfig > RCU implementation type: > > 1. Classic RCU (CLASSIC_RCU) (NEW) > 2. Preemptible RCU (PREEMPT_RCU) (NEW) > choice[1-2]: ? > > Sorry, no help available for this option yet. Good catch!!! This patch supplies help text for the "RCU implementation type" kernel configuration choice. Signed-off-by: Paul E. McKenney --- Kconfig.preempt | 8 ++++++++ 1 file changed, 8 insertions(+) diff -urpNa -X dontdiff linux-2.6.24-rt1/kernel/Kconfig.preempt linux-2.6.24-rt1-RCUconfighelp/kernel/Kconfig.preempt --- linux-2.6.24-rt1/kernel/Kconfig.preempt 2008-01-27 02:52:36.000000000 -0800 +++ linux-2.6.24-rt1-RCUconfighelp/kernel/Kconfig.preempt 2008-01-27 03:05:22.000000000 -0800 @@ -131,6 +131,14 @@ choice prompt "RCU implementation type:" default PREEMPT_RCU if PREEMPT_RT default CLASSIC_RCU + help + This allows you to choose either the classic RCU implementation + that is designed for best read-side performance on non-realtime + systems, or the preemptible RCU implementation for best latency + on realtime systems. Note that some kernel preemption modes + will restrict your choice. + + Select the default if you are unsure. config CLASSIC_RCU bool "Classic RCU"