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Subject: Re: [patch] Prefetching file_read_actor()
To: davej@suse.de (Dave Jones)
Date: Tue, 1 Jan 2002 10:29:20 +0000 (GMT)
Cc: akpm@zip.com.au (Andrew Morton), manfred@colorfullife.com (Manfred Spraul),
        linux-kernel@vger.kernel.org (Linux Kernel)
In-Reply-To: <Pine.LNX.4.33.0112312045130.17274-100000@Appserv.suse.de> from "Dave Jones" at Dec 31, 2001 08:47:43 PM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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> My initial guess is that some of the callers of copy_to_user are
> doing something that is harmed the prefetching.
> (Maybe they are doing additional prefetch() calls)

Most callers are dealing with cached data, and unless you checked the
length in advance to make a sensible decision it will just make things ugly.
If you aren't copying 512 bytes+ its probably not worth it.

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