Re: i686 quirk for AMD Geode

Matteo Croce
2009-11-06T22:18:23Z

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
gcc -c -O3 -march=i586 ./dry.c -o dry1.o
gcc -DPASS2 -O3 -march=i586 ./dry.c dry1.o -o dry2

Dhrystone Benchmark, Version C, Version 2.2
Program compiled without 'register' attribute
Using times(), HZ=100

Trying 5000000 runs through Dhrystone:
Microseconds for one run through Dhrystone: 1.4
Dhrystones per Second: 740741

root@alix:/usr/src# CFLAGS='-march=i686' ./dry.c
gcc -c -O3 -march=i686 ./dry.c -o dry1.o
gcc -DPASS2 -O3 -march=i686 ./dry.c dry1.o -o dry2

Dhrystone Benchmark, Version C, Version 2.2
Program compiled without 'register' attribute
Using times(), HZ=100

Trying 5000000 runs through Dhrystone:
Microseconds for one run through Dhrystone: 1.2
Dhrystones per Second: 841751