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Subject: Re: [beta patch] SSE copy_page() / clear_page()
To: pavel@suse.cz (Pavel Machek)
Date: Tue, 20 Feb 2001 20:49:49 +0000 (GMT)
Cc: manfred@colorfullife.com (Manfred Spraul),
        torvalds@transmeta.com (Linus Torvalds), linux-kernel@vger.kernel.org
In-Reply-To: <20010220183513.B5102@bug.ucw.cz> from "Pavel Machek" at Feb 20, 2001 06:35:13 PM
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> > +		__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

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