Thanks for the input.
> > a 3 % reduction in the Memory Index benchmark
> > a 2 % increase in the Integer Index benchmark
> > a 23 % reduction in the Floating Point Index
> Small fluctuations in the range of 2 or 3 percent
> are usually explained
> by a changing usage pattern of the caches.
> Therefore rerunning a the
> benchmarks is a good idea. Especially
> microbenchmarks a la lmbench on
> caches of low associativity like the direct mapped
> R4k caches are extremly
> easily affected by cache usage patterns.
I messed up the figures for the redhat 7.1 case They
should have been :
Memory Index 6.7 % decrease
Integer Index 2 % decrease
Floating Point 27 % decrease
And it was the progressive reduction in performance of
the Memory Index that was raising a red flag to me.
Especially the big hit in floating point performance.
> Did you get any kernel messages during the Floating
> Point Index benchmark
> on the older kernel?
No, everything ran fine.
> > newer kernel and with a newer distribution ? newer
> > compiler ?
> Gcc 3.0 has been reported to produce slightly slower
> code than it's
> predecessor by many people on various architecture.
> I'm sad to find that
> MIPS is also one of them.
OK. That's one to remember.
> As for the kernel - I don't really know; your
> analysis isn't fine grained
I didn't do any performance tweaking with the kernel
itself as I wouldn't really know how to go about it. I
was more trying to use a base kernel and then see how
I could improve the benchmark performance by using
compile options on the benchmark program only.
Admittedly improving kernel performance is a far more
efficient way of improving the benchmark scores.
> Successful tuning requires a detailed analysis
I read an article recently in Linux Journal on
tweaking an Alpha kernel. I suppose the same general
principles can be applied to MIPS. Alternatively, do
you ( or anyone else ) know of a howto or even a
general article on how to do this ?
I downloaded the benchmark from :
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