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SubjectRe: [PATCH] use movntq version of fast_clear_page/fast_copy_page on Geode
On Wed, Feb 14, 2007 at 06:17:36PM -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?

I don't, and my 3dnow capable C3s are unplugged right now.
The newer generation (including the C7) have SSE/SSE2 instead,
which seems to be faster. (Using a different benchmark app that uses SSE)

clear_page function 'normal clear_page()' took 9425 cycles per page (620.3 MB/s)
clear_page function 'new clear_page() ' took 3840 cycles per page (1522.7 MB/s)

copy_page function 'normal copy_page()' took 11453 cycles per page (510.5 MB/s)
copy_page function 'new copy_page() ' took 5024 cycles per page (1163.7 MB/s)


Dave

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