Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750867Ab3IFIIb (ORCPT ); Fri, 6 Sep 2013 04:08:31 -0400 Received: from mail-pb0-f47.google.com ([209.85.160.47]:35709 "EHLO mail-pb0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750808Ab3IFIIX (ORCPT ); Fri, 6 Sep 2013 04:08:23 -0400 MIME-Version: 1.0 In-Reply-To: <1376966841-31774-8-git-send-email-paulmck@linux.vnet.ibm.com> References: <20130820024700.GA31075@linux.vnet.ibm.com> <1376966841-31774-1-git-send-email-paulmck@linux.vnet.ibm.com> <1376966841-31774-8-git-send-email-paulmck@linux.vnet.ibm.com> Date: Fri, 6 Sep 2013 10:08:22 +0200 X-Google-Sender-Auth: oqhhN00C_a096kOIlv8gufCANW4 Message-ID: Subject: Re: [PATCH tip/core/rcu 8/9] nohz_full: Add full-system-idle state machine From: Geert Uytterhoeven To: "Paul E. McKenney" Cc: "linux-kernel@vger.kernel.org" , Ingo Molnar , laijs@cn.fujitsu.com, dipankar@in.ibm.com, Andrew Morton , Mathieu Desnoyers , josh@joshtriplett.org, niv@us.ibm.com, Thomas Gleixner , Peter Zijlstra , Steven Rostedt , David Howells , edumazet@google.com, darren@dvhart.com, =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= , sbw@mit.edu, Linux-Arch , linux-kbuild Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1881 Lines: 52 On Tue, Aug 20, 2013 at 4:47 AM, Paul E. McKenney wrote: > --- a/kernel/time/Kconfig > +++ b/kernel/time/Kconfig > @@ -157,6 +157,33 @@ config NO_HZ_FULL_SYSIDLE > > Say N if you are unsure. > > +config NO_HZ_FULL_SYSIDLE_SMALL > + int "Number of CPUs above which large-system approach is used" > + depends on NO_HZ_FULL_SYSIDLE > + range 1 NR_CPUS This causes "kernel/time/Kconfig:162:warning: range is invalid" on m68k and all other architectures that do not support SMP. How to reproduce: make ARCH=m68k defconfig Furthermore, it seems only hexagon, metag, mips, and x86 set NR_CPUS to 1 if !SMP. On other architectures, NR_CPUS is not defined and presumed to be 0. Hence in non-interactive configs (e.g. "make defconfig"), NO_HZ_FULL_SYSIDLE_SMALL will end up as 0. In interactive configs (e.g. "make oldconfig") Kconfig suggest "0" as the default, but refuses to accept it as it doesn't fall within the range 1..0. How to reproduce: Remove the "depends on NO_HZ_FULL_SYSIDLE" make ARCH=powerpc mpc83xx_defconfig grep NO_HZ_FULL_SYSIDLE_SMALL .config -> CONFIG_NO_HZ_FULL_SYSIDLE_SMALL=0 sed 's/CONFIG_NO_HZ_FULL_SYSIDLE_SMALL=0//g' -i .config make ARCH=powerpc oldconfig -> no value is accepted Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- 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/