From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751300Ab2CaQy5 (ORCPT ); Sat, 31 Mar 2012 12:54:57 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:50295 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750944Ab2CaQy4 (ORCPT ); Sat, 31 Mar 2012 12:54:56 -0400 Date: Sat, 31 Mar 2012 09:54:01 -0700 From: "Paul E. McKenney" To: Geert Uytterhoeven Cc: linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, uclinux-dist-devel@blackfin.uclinux.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m32r@ml.linux-m32r.org, linux-m32r-ja@ml.linux-m32r.org, linux-mips@linux-mips.org, linux-am33-list@redhat.com, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, tglx@linutronix.de, linux@arm.linux.org.uk, dhowells@redhat.com, jejb@parisc-linux.org, linux390@de.ibm.com, x86@kernel.org, cmetcalf@tilera.com, linux-m68k Subject: Re: [PATCH RFC] Simplify the Linux kernel by reducing its state space Message-ID: <20120331165401.GD2450@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20120331163321.GA15809@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12033116-2398-0000-0000-0000057A47C8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Mar 31, 2012 at 06:40:30PM +0200, Geert Uytterhoeven wrote: > Hi Paul, > > On Sat, Mar 31, 2012 at 18:33, Paul E. McKenney > wrote: > > Although there have been numerous complaints about the complexity of > > parallel programming (especially over the past 5-10 years), the plain > > truth is that the incremental complexity of parallel programming over > > that of sequential programming is not as large as is commonly believed. > > Despite that you might have heard, the mind-numbing complexity of modern > > computer systems is not due so much to there being multiple CPUs, but > > rather to there being any CPUs at all.  In short, for the ultimate in > > computer-system simplicity, the optimal choice is NR_CPUS=0. > > > > This commit therefore limits kernel builds to zero CPUs.  This change > > has the beneficial side effect of rendering all kernel bugs harmless. > > Furthermore, this commit enables additional beneficial changes, for > > example, the removal of those parts of the kernel that are not needed > > when there are zero CPUs. > > > > Signed-off-by: Paul E. McKenney > > Reviewed-by: Thomas Gleixner > > --- > > > >  alpha/Kconfig                     |   11 ++++++----- > >  arm/Kconfig                       |    6 +++--- > >  blackfin/Kconfig                  |    3 ++- > >  hexagon/Kconfig                   |    9 +++++---- > >  ia64/Kconfig                      |    9 +++++---- > >  m32r/Kconfig                      |   10 ++++++---- > >  mips/Kconfig                      |   21 +++++++++++---------- > >  mn10300/Kconfig                   |    3 ++- > >  parisc/Kconfig                    |    6 +++--- > >  powerpc/platforms/Kconfig.cputype |    8 ++++---- > >  s390/Kconfig                      |   12 +++++++----- > >  sh/Kconfig                        |   11 ++++++----- > >  sparc/Kconfig                     |    8 ++++---- > >  tile/Kconfig                      |    9 +++++---- > >  x86/Kconfig                       |   16 +++++++++------- > >  15 files changed, 78 insertions(+), 64 deletions(-) > > You forgot to fix half of the architectures, a.o. m68k? I must confess that I fixed only the SMP-capable architectures. I of course would welcome additions for UP-only architectures. Thanx, Paul