Re: i686 quirk for AMD Geode

Pavel Machek
2009-11-08T17:37:12Z

On Fri 2009-11-06 23:18:06, Matteo Croce wrote:
> On Fri, Nov 6, 2009 at 5:44 PM, H. Peter Anvin <hpa@zytor.com> wrote:
> > On 11/06/2009 06:59 AM, Matteo Croce wrote:
> >> indeed it has MMX, MMXEXT and CMOV, just lacks the long NOP instruction (NOPL).
> >
> > MMX and MMXEXT are hardly hallmarks of i686, which leaves only cmov.
> > I'm somewhat wondering about the general value of this patch; is i686
> > code really that much faster on Geode that it's worth it?
> >
> > ? ? ? ?-hpa
> >
> > --
> > H. Peter Anvin, Intel Open Source Technology Center
> > I work for Intel. ?I don't speak on their behalf.
> >
> >
>
> yes, I did some test like gzip, bzip2, lame etc and they give more or less
> the same results of dhrystone
>
> root@alix:/usr/src# CFLAGS='-march=i586' ./dry.c
> Microseconds for one run through Dhrystone: 1.4
> Dhrystones per Second: 740741
...
> root@alix:/usr/src# CFLAGS='-march=i686' ./dry.c
> Trying 5000000 runs through Dhrystone:
> Microseconds for one run through Dhrystone: 1.2
> Dhrystones per Second: 841751

Teach gcc that geodelx exists? No need to break kernel for that... and
you probably can gain even bigger gains.
Pavel

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