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Date: Sun, 3 Nov 2013 11:18:25 +0100 From: Ingo Molnar <mingo@...nel.org> To: Josh Boyer <jwboyer@...hat.com> Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>, prarit@...hat.com, x86@...nel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] x86: Allow NR_CPUS=1024 * Josh Boyer <jwboyer@...hat.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@...oraproject.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. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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