From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758446Ab2EaUbL (ORCPT ); Thu, 31 May 2012 16:31:11 -0400 Received: from merlin.infradead.org ([205.233.59.134]:40747 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758411Ab2EaUbJ convert rfc822-to-8bit (ORCPT ); Thu, 31 May 2012 16:31:09 -0400 Message-ID: <1338496257.28384.121.camel@twins> Subject: Re: [PATCH] sched/x86: Calculate booted cores after construction of sibling_mask From: Peter Zijlstra To: Kamalesh Babulal Cc: linux-kernel@vger.kernel.org, mingo@redhat.com Date: Thu, 31 May 2012 22:30:57 +0200 In-Reply-To: <20120531073738.GH7511@linux.vnet.ibm.com> References: <20120531073738.GH7511@linux.vnet.ibm.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2012-05-31 at 13:07 +0530, Kamalesh Babulal wrote: > While booting tip (1d06e6d354) on qemu with -smp sockets=1,cores=2,threads=2 > topology. There is a mismatch between the number of cores actually present > and cores reported. > > Changes related to calculating the number of booted cores was introduced > by 316ad248307fb (sched/x86: Rewrite set_cpu_sibling_map()). With the > clean up, the calculation of booted cores per package is done on an > incompletely constructed sibling_mask per cpu. > > sched/x86: Calculate booted cores after construction of sibling_mask Why repeat this subject again? > This patch re-introduces the old behaviour of constructing the complete > sibling mask of the cpu, before calculating the number of cores booted. > Signed-off-by: Kamalesh Babulal > --- > arch/x86/kernel/smpboot.c | 7 ++++++- > 1 files changed, 6 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c > index fd019d7..a8d78f3 100644 > --- a/arch/x86/kernel/smpboot.c > +++ b/arch/x86/kernel/smpboot.c > @@ -382,7 +382,12 @@ void __cpuinit set_cpu_sibling_map(int cpu) > if ((i == cpu) || (has_mc && match_llc(c, o))) > link_mask(llc_shared, cpu, i); > > - if ((i == cpu) || (has_mc && match_mc(c, o))) { > + } > + > + for_each_cpu(i, cpu_sibling_setup_mask) { > + o = &cpu_data(i); > + > + if ((i == cpu) || (has_mc && match_mc(c, o))) { > link_mask(core, cpu, i); > > /* This patch actually horribly mangles the indenting. I did the below to it: --- Subject: sched/x86: Calculate booted cores after construction of sibling_mask From: Kamalesh Babulal Date: Thu, 31 May 2012 13:07:38 +0530 Commit 316ad248307fb ("sched/x86: Rewrite set_cpu_sibling_map()") broke the booted_cores accounting. The problem is that the booted_cores accounting needs all the sibling links set up. So restore the second loop and add a comment as to why its needed. On qemu booted with -smp sockets=1,cores=2,threads=2; Before: $ grep cores /proc/cpuinfo cpu cores : 2 cpu cores : 1 cpu cores : 4 cpu cores : 3 With the patch: $ grep cores /proc/cpuinfo cpu cores : 2 cpu cores : 2 cpu cores : 2 cpu cores : 2 Signed-off-by: Kamalesh Babulal Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20120531073738.GH7511@linux.vnet.ibm.com --- arch/x86/kernel/smpboot.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -382,6 +382,15 @@ void __cpuinit set_cpu_sibling_map(int c if ((i == cpu) || (has_mc && match_llc(c, o))) link_mask(llc_shared, cpu, i); + } + + /* + * This needs a separate iteration over the cpus because we rely on all + * cpu_sibling_mask links to be set-up. + */ + for_each_cpu(i, cpu_sibling_setup_mask) { + o = &cpu_data(i); + if ((i == cpu) || (has_mc && match_mc(c, o))) { link_mask(core, cpu, i);