Messages in this thread | | | Date | Sun, 3 Nov 2013 08:42:27 -0600 | From | Russ Anderson <> | Subject | Re: [PATCH] x86: Allow NR_CPUS=1024 |
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On Sun, Nov 03, 2013 at 09:29:16AM -0500, Prarit Bhargava wrote: > On 11/03/2013 05:18 AM, Ingo Molnar wrote: > > > > * Josh Boyer <jwboyer@redhat.com> wrote: > > > >> The current range for SMP configs is 2 - 512, or a full 4096 in the case > >> of MAXSMP. There are machines that have 1024 CPUs in them today and > >> configuring a kernel for that means you are forced to set MAXSMP. This > >> adds additional unnecessary overhead. While that overhead might be > >> considered tiny for large machines, it isn't necessarily so if you are > >> building a kernel that runs across a wide variety of machines. We > >> increase the range to 1024 to help with this. > >> > >> Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org> > >> --- > >> arch/x86/Kconfig | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > >> index f67e839..d726b2d 100644 > >> --- a/arch/x86/Kconfig > >> +++ b/arch/x86/Kconfig > >> @@ -825,7 +825,7 @@ config MAXSMP > >> 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 > >> + range 2 1024 if SMP && !MAXSMP > >> default "1" if !SMP > >> default "4096" if MAXSMP > >> default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000) > > > > Any reason not to allow it to go up to 4096? The original concern was that > > CPUS=4096 wasn't working very well and you had to select MAXSMP > > deliberately and keep all the pieces. > > > > But today it's all pretty robust so I see no reason why not to allow up to > > 4096 CPUs. > > Adding Russ from SGI as they are one of the consumers of a large CPU count. > > I have no objections to raising this to 4096 FWIW. I think it is a good idea, > and it is long overdue.
I obviously agree with increasing to 4096. The bigger the better.
-- Russ Anderson, OS RAS/Partitioning Project Lead SGI - Silicon Graphics Inc rja@sgi.com
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