Re: [PATCH] x86: allow 8 more cpus could be used

From: Ingo Molnar
Date: Thu Jan 29 2009 - 18:13:25 EST



* Randy Dunlap <randy.dunlap@xxxxxxxxxx> wrote:

> Ingo Molnar wrote:
> > * Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> >
> >> Impact: fix left out MARCO
> >>
> >> X86_PC will be always enabled. so need to check if we have bigsmp
> >> support built in before cut off more than 8 cpus.
> >
> > ah, that's a leftover reference to X86_PC. It can now be removed, together
> > with the Kconfig X86_PC option.
> >
> >> -#if defined(CONFIG_X86_PC) && defined(CONFIG_X86_32)
> >> +#if defined(CONFIG_X86_PC) && !defined(CONFIG_X86_BIGSMP)
> >> if (def_to_bigsmp && nr_cpu_ids > 8) {
> >> unsigned int cpu;
> >> unsigned nr;
> >
> > Could you please send a patch that removes both X86_PC and X86_BIGSMP -
> > and removes the above cutoff code too, so that it will be built-in all the
> > time?
>
> and at what cost, please?

the size difference between a bigsmp and a normal-smp x86 defconfig kernel
is 0.011%. Zero difference on a UP kernel. (And UP is what most of the
ultra-embedded systems are using)

Ingo
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