Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764308AbYCEA6d (ORCPT ); Tue, 4 Mar 2008 19:58:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751800AbYCEA6W (ORCPT ); Tue, 4 Mar 2008 19:58:22 -0500 Received: from e34.co.us.ibm.com ([32.97.110.152]:58342 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751642AbYCEA6V (ORCPT ); Tue, 4 Mar 2008 19:58:21 -0500 Date: Tue, 4 Mar 2008 16:58:16 -0800 From: "Paul E. McKenney" To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, ego@in.ibm.com, Ingo Molnar , Dipankar Sarma , Ted Tso , dvhltc@us.ibm.com, Oleg Nesterov , Andrew Morton , bunk@kernel.org, Josh Triplett , Thomas Gleixner , Peter Zijlstra , zippel@linux-m68k.org Subject: Re: [PATCH] move PREEMPT_RCU config option back under PREEMPT Message-ID: <20080305005816.GG9517@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20071213170348.GA25981@in.ibm.com> <20071213171658.GE25981@in.ibm.com> <200802290534.57040.zippel@linux-m68k.org> <20080229045328.GA18687@linux.vnet.ibm.com> <20080301193903.GC15887@linux.vnet.ibm.com> <20080303185511.GE12453@linux.vnet.ibm.com> <20080304202207.GA10926@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Content-Length: 1982 Lines: 50 On Tue, Mar 04, 2008 at 03:55:42PM -0500, Steven Rostedt wrote: > > On Tue, 4 Mar 2008, Paul E. McKenney wrote: > > > > The original preemptible-RCU patch put the choice between classic and > > preemptible RCU into kernel/Kconfig.preempt, which resulted in build > > failures on machines not supporting CONFIG_PREEMPT. This choice was > > therefore moved to init/Kconfig, which worked, but placed the choice > > between classic and preemptible RCU at the top level, a very obtuse choice > > indeed. This patch changes from the Kconfig "choice" mechanism to a pair > > of booleans, only one of which (CONFIG_PREEMPT_RCU) is user-visible, > > and is located in kernel/Kconfig.preempt, where one would expect it > > to be. The other (CONFIG_CLASSIC_RCU) is in init/Kconfig so that it > > is available to all architectures, hopefully avoiding build breakage. > > Thanks to Roman Zippel for suggesting this approach. > > > > I have tested this, but sadly do not have access to a machine that does > > not support CONFIG_PREEMPT. However, I did edit my config in an attempt > > to simulate this situation. > > One minor comment, but otherwise: > > Acked-by: Steven Rostedt > > > > > Signed-off-by: Paul E. McKenney > > > > config CLASSIC_RCU > > - bool "Classic RCU" > > + def_bool !PREEMPT_RCU > > help > > This option selects the classic RCU implementation that is > > designed for best read-side performance on non-realtime > > - systems. > > - > > - Say Y if you are unsure. > > - > > You can get rid of the "help" part since it isn't visible to users. So how about if I replace it with comment lines (starting with "#", not with "comment")? Thanx, Paul -- 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/