Re: [patch] Prefetching file_read_actor()

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Andrew Morton wrote:
>
>
> Is prefetching 4k at a time optimal? Should the prefetch be embedded
> in copy_*_user?
>
For the Pentium III, that's the Intel recommended sequence.

>
> The code makes no attempt to align the prefetch address to anything.
> Should it?

Not needed.

> What happens if a prefetch spills over the end of the page and
> faults?
>
Doesn't hurt, prefetch instruction never cause page faults.
BUT: Prefetch doesn't preload the TLB. If the TLB entry for the kmap is
not in the TLB, all prefetch instructions are treated as nops.(on pIII).

--
	Manfred
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