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Date: Mon, 31 Dec 2001 11:58:27 +0100
From: Manfred Spraul <manfred@colorfullife.com>
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To: Andrew Morton <akpm@zip.com.au>
CC: Dave Jones <davej@suse.de>, Linux Kernel <linux-kernel@vger.kernel.org>
Subject: 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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