Re: [beta patch] SSE copy_page() / clear_page()

[Pavel Machek]

> > > +		__asm__ __volatile__(
> > > +			"mov %1, %0\n\t"
> > > +			: "=r" (i)
> > > +			: "r" (kaddr+offset)); /* load tlb entry */
> > > +		for(i=0;i<size;i+=64) {
> > > +			__asm__ __volatile__(
> > > +				"prefetchnta (%1, %0)\n\t"
> > > +				"prefetchnta 32(%1, %0)\n\t"
> > > +				: /* no output */
> > > +				: "r" (i), "r" (kaddr+offset));
> > > +		}
> > > +	}
> > >  	left = __copy_to_user(desc->buf, kaddr + offset, size);
> > >  	kunmap(page);
> > 
> > This seems bogus -- you need to handle faults --
> > i.e. __prefetchnta_to_user() ;-).
> 
> It wants wrapping nicely. A generic prefetch and prefetchw does help some other
> cases (scheduler for one).
> 
> Does the prefetch instruction fault on PIII/PIV then - the K7 one appears not
> to be a source of faults

My fault. I was told that prefetch instructions are always
non-faulting.

				Pavel

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The best software in life is free (not shareware)!		Pavel
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