Re: [-mm patch] {rd,wr}msr_on_cpu SMP=n optimization

From: Alexey Dobriyan
Date: Tue Feb 20 2007 - 08:45:05 EST


On Mon, Feb 19, 2007 at 07:14:34PM -0500, Dave Jones wrote:
> On Tue, Feb 20, 2007 at 01:07:13AM +0100, Adrian Bunk wrote:
> > On Thu, Feb 15, 2007 at 05:14:08AM -0800, Andrew Morton wrote:
> > >...
> > > Changes since 2.6.20-rc6-mm3:
> > >...
> > > +rdmsr_on_cpu-wrmsr_on_cpu.patch
> > >...
> > > x86 updates
> > >...
> >
> > Let's save a few bytes in the CONFIG_SMP=n case.
> >
> > Signed-off-by: Adrian Bunk <bunk@xxxxxxxxx>
> >
> > ---
> >
> > BTW: currently -ENOUSERS
>
> There was a follow-on patch that converted p4-clockmod to use it for one.

And patch for powernow-k8 in preparations.

> > +#ifdef CONFIG_SMP
> > void rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
> > void wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);
> > +#else /* CONFIG_SMP */
> > +static inline void rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
> > +{
> > + rdmsr(msr_no, *l, *h);
> > +}
> > +static inline void wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
> > +{
> > + wrmsr(msr_no, l, h);
> > +}
> > +#endif /* CONFIG_SMP */
>
> BUG_ON(cpu!=smp_processor_id()) maybe?

This make sense. Fell free to add it.

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