Re: AMD Geode GX/LX Support (Refreshed)

[Jordan Crouse]

> >  config X86_USE_PPRO_CHECKSUM
> Does this mean you've now done actual performance analysis on whether
> this is a good idea for Geode GX/LX ?

Ok - here is some data that should put your mind at ease.  I pulled
the checksum functions from the kernel, stuck them in userland, and
ran each one N times at a variety of byte sizes (where N=10,000), took the
start and stop times with gettimeofday(), and added it all up.  The results
for the Geode LX platfrom are below.

I think the data shows that the ppro checksum is indeed useful on the
Geode LX platform (and the GX should have similar results, since the
pipelines are pretty close).  Unless I made a really boneheaded mistake
in my app, I think we should leave X86_USE_PPRO_CHECKSUM enabled for Geode
GX/LX.

Jordan

Starting non-ppro test....
Bytes   Time    Avg (usec/run)
----------------------------
16      2029    0.202900
32      1666    0.166600
64      2548    0.254800
128     3429    0.342900
256     5268    0.526800
512     8781    0.878100
1024    16031   1.603100
2048    30548   3.054800
4096    59265   5.926500
Total time: 129565

Starting ppro test....
Bytes   Time    Avg (usec/run)
----------------------------
16      1579    0.157900
32      1655    0.165500
64      1841    0.184100
128     2721    0.272100
256     3582    0.358200
512     5264    0.526400
1024    8900    0.890000
2048    15919   1.591900
4096    29369   2.936900
Total time: 70830

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