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SubjectRe: [PATCH] use movntq version of fast_clear_page/fast_copy_page on Geode
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On Wed, 2007-02-14 at 18:17 -0200, Marcelo Tosatti wrote:
> On Wed, Feb 14, 2007 at 02:55:46PM -0500, Dave Jones wrote:
> > On Wed, Feb 14, 2007 at 05:08:39PM -0200, Marcelo Tosatti wrote:
> > >
> > > movntq instruction is supported by Geode CPU's, so use
> > > fast_clear_page/fast_copy_page versions that have it.
> >
> > it's supported, but is it a win ?
> > The same was also true of the VIA C3/C7's, but due to
> > poor memory bandwidth, it turned out to be slower in most cases.
>
> Do you have the numbers for VIA C3/C7 around?
>
> The Geode benefits from movntq instead of movq:
>
> [marcelo@localhost ~]$ cat /proc/cpuinfo
> processor : 0
> vendor_id : Geode by NSC
> cpu family : 5
> model : 5
> model name : Geode(TM) Integrated Processor by National Semi
> stepping : 2
> cpu MHz : 364.898
> cache size : 32 KB
> ...
>
> [marcelo@localhost ~]$ wget http://www.fenrus.demon.nl/athlon.c
> ...


btw there is a caveat with this program: you don't see that this evicts
the data RIGHT AFTER THE COPY, so if you use it again you pay AGAIN the
memory bandwidth price...

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