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Subject: Re: [patch] Prefetching file_read_actor()
To: akpm@zip.com.au (Andrew Morton)
Date: Mon, 31 Dec 2001 13:00:21 +0000 (GMT)
Cc: davej@suse.de (Dave Jones), linux-kernel@vger.kernel.org (Linux Kernel),
        manfred@colorfullife.com (Manfred Spraul)
In-Reply-To: <3C2FFB2F.D02095A2@zip.com.au> from "Andrew Morton" at Dec 30, 2001 09:44:15 PM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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> > +
> > +       if (size > 128) {
> > +               int i;
> > +               for(i=0; i<size; i+=64) {
> > +                       prefetch (kaddr+offset);
> > +                       prefetch (kaddr+offset+(L1_CACHE_BYTES*2));
> > +               }
> > +       }
> > +

Thats almost certainly wrong for most processors. It might work on the PIII
but I wouldnt trust the right results on others. Fix copy_to_user to
have a prefetching version if appropriate

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