Re: [PATCH 1/2] i386: mce cleanup part1: functional change

Valdis.Kletnieks
2007-10-09T20:47:11Z

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On Tue, 09 Oct 2007 18:32:30 +0200, Oleg Verych said:
> On Tue, Oct 09, 2007 at 06:06:05PM +0200, Joerg Roedel wrote:
> > > cpu_has() returns int,
> > > but would it be better to have something like
> > >
> > > if (!mce_disabled &&
> > > !(c->x86_capability & (X86_FEATURE_MCA | X86_FEATURE_MCE)) {
> > > printk(KERN_INFO "CPU%i: No machine check support available\n",
> > > smp_processor_id());
> >
> > This looks complicated and is harder to read. Its exactly the purpose of the
> > cpu_has() macro to avoid such constructs.
>
> It is done via test_bit(), which is designed for IO access with all that
> `const volatile' stuff, 2 x unnecessary, can't be optimized here (IMHO).

If this code is getting called often enough that optimization matters, you
got *bigger* issues to worry about than optimization. Looks like it should
only happen once at boot time.

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