linux-kernel - Re: [PATCH] x86: try to simplify NR

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Message-ID: <CA+55aFymknkNH2mP1vX5ZLEqQwA3BgxQhZF-SUbbJMwTDL6hAA@mail.gmail.com>
Date:   Fri, 9 Feb 2018 14:39:26 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: try to simplify NR_CPUS config

On Fri, Feb 9, 2018 at 2:01 PM, Randy Dunlap <rdunlap@...radead.org> wrote:
>
> This is a rather literal interpretation of Linus's suggestion.

I think it can be simplified a bit more.

If you move the definition of RANGE_END_CPUS up to before
RANGE_BEGIN_CPUS, you can then make the RANGE_BEGIN_CPUS just be
something like

   default 1 if !SMP
   default RANGE_END_CPUS if MAXSMP
   default 2

which makes a whole lot more sense.

and if you split that RANGE_END_CPUS so that the x86-32 and x86-64
cases are separate, that makes *those* more understandable. It also
makes sense to separate since X86_BIGSMP is 32-bit only.

But yes, this looks like it's in the right direction, where we can
make each step be fairly obvious, instead of the current NR_CPUS mess
that is entirely impossible to parse for mere humans.

               Linus