From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751274Ab3KFF4i (ORCPT ); Wed, 6 Nov 2013 00:56:38 -0500 Received: from mail-ea0-f170.google.com ([209.85.215.170]:43197 "EHLO mail-ea0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750803Ab3KFF4h (ORCPT ); Wed, 6 Nov 2013 00:56:37 -0500 Date: Wed, 6 Nov 2013 06:56:34 +0100 From: Ingo Molnar To: Josh Boyer , Linus Torvalds , Andrew Morton Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , prarit@redhat.com, x86@kernel.org, linux-kernel@vger.kernel.org, Russ Anderson Subject: [PATCH v2 2/2] x86: Increase MAXSMP CPU count to 8192 Message-ID: <20131106055634.GA24044@gmail.com> References: <20131101141148.GH8652@hansolo.jdub.homelinux.org> <20131105143728.GJ9944@hansolo.jdub.homelinux.org> <20131105143816.GK9944@hansolo.jdub.homelinux.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131105143816.GK9944@hansolo.jdub.homelinux.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Josh Boyer wrote: > The MAXSMP option is intended to enable silly large numbers of CPUs for > testing purposes. The current value of 4096 isn't very silly any longer > as there are actual machines that approach 6096 CPUs when taking HT into > account. Increase the value to 8192 to account for this and short term > future increases. > > Signed-off-by: Josh Boyer > --- > arch/x86/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index f03e428..09f05cd 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -828,7 +828,7 @@ config NR_CPUS > range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK > range 2 4096 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64 > default "1" if !SMP > - default "4096" if MAXSMP > + default "8192" if MAXSMP So I changed the patch to up the regular range to 8192 as well: it's more consistent if MAXSMP tracks the normal range, as long as the defaults are sane. See the commit below. Note that 'normal users' won't ever see any max CPU count beyond the current 512 (which is already kind of crazy for normal use), because CPUMASK_OFFSTACK is turned off on all but MAXSMP configs (unless the user explicitly enables the option). So it's not really possible to accidentally wander into that option and set it to an insane value - it takes some effort. [ I've Cc:-ed Linus, who had a strong opinion about these max-cpu limits in the past - I hope the changes are fine in this form. ] Thanks, Ingo =====================> >>From 07bce9fd69e8409740e63db0ab0755b84ee61a0c Mon Sep 17 00:00:00 2001 From: Josh Boyer Date: Tue, 5 Nov 2013 09:38:16 -0500 Subject: [PATCH] x86/cpu: Increase max CPU count to 8192 The MAXSMP option is intended to enable silly large numbers of CPUs for testing purposes. The current value of 4096 isn't very silly any longer as there are actual SGI machines that approach 6096 CPUs when taking HT into account. Increase the value to a nice round 8192 to account for this and allow for short term future increases. Signed-off-by: Josh Boyer Cc: prarit@redhat.com Cc: Russ Anderson Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/r/20131105143816.GK9944@hansolo.jdub.homelinux.org [ Tweaked it so that MAXSMP simply sets the maximum of the normal range. ] Signed-off-by: Ingo Molnar --- arch/x86/Kconfig | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f03e428..805469a 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -826,9 +826,9 @@ config NR_CPUS int "Maximum number of CPUs" if SMP && !MAXSMP range 2 8 if SMP && X86_32 && !X86_BIGSMP range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK - range 2 4096 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64 + range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64 default "1" if !SMP - default "4096" if MAXSMP + default "8192" if MAXSMP default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000) default "8" if SMP ---help---