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Subject: Re: [RFC] [PATCH] cache pollution aware __copy_from_user_ll()
From: Arjan van de Ven <arjan@infradead.org>
To: hyoshiok@miraclelinux.com
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Date: Sun, 14 Aug 2005 11:41:28 +0200
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On Sun, 2005-08-14 at 18:16 +0900, Hiro Yoshioka wrote:
> Hi,
> 
> The following is a patch to reduce a cache pollution
> of __copy_from_user_ll().
> 
> When I run simple iozone benchmark to find a performance bottleneck of
> the linux kernel, I found that __copy_from_user_ll() spent CPU cycle
> most and it did many cache misses.


however... you copy something from userspace... aren't you going to USE
it? The non-termoral versions actually throw the data out of the
cache... so while this part might be nice, you pay BIG elsewhere....