On Wed, Nov 06, 2013 at 06:56:34AM +0100, Ingo Molnar wrote: > > * Josh Boyer <jwbo...@redhat.com> 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 <jwbo...@fedoraproject.org> > > --- > > 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.
OK. That looks fine to me. > 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. ] Me too. josh > > Thanks, > > Ingo > > =====================> > From 07bce9fd69e8409740e63db0ab0755b84ee61a0c Mon Sep 17 00:00:00 2001 > From: Josh Boyer <jwbo...@redhat.com> > 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 <jwbo...@fedoraproject.org> > Cc: pra...@redhat.com > Cc: Russ Anderson <r...@sgi.com> > Cc: Linus Torvalds <torva...@linux-foundation.org> > Cc: Andrew Morton <a...@linux-foundation.org> > Link: > http://lkml.kernel.org/r/20131105143816.gk9...@hansolo.jdub.homelinux.org > [ Tweaked it so that MAXSMP simply sets the maximum of the normal range. ] > Signed-off-by: Ingo Molnar <mi...@kernel.org> > --- > 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--- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
