[maemo-developers] [maemo-developers] Speed test with vfp (floating point) on N800

[From: Simon Pickering]

> I was very interesseted in the floating point copro in the 
> N800 cpu and did some tests with a progamm which calculates 
> the mandelbrod set and outputs it via SDL. I put this program 
> online on bomberman.garage.maemo.org. No installer, you have 
> to run the benchmarks on xterm or via ssh (so did I).

For reference, I've also got some benchmark results. I compiled whetstone, flops
and dhrystone (and paranoia) for the 770, N800 and my desktop PC (for
comparison).

Results here: 
http://people.bath.ac.uk/enpsgp/benchmarks/N800-fp-tests.txt
http://people.bath.ac.uk/enpsgp/benchmarks/770-fp-tests.txt
http://people.bath.ac.uk/enpsgp/benchmarks/PC-fp-tests.txt

Binaries here:
http://people.bath.ac.uk/enpsgp/benchmarks/

My apologies for the layout of the txt files, I'm in the process of tidying them
up and putting up a results page.

Curiously the 770 performs better for dhrystone with optimisation than the N800,
but these results were variable and should probably be run with a very large
number of iterations to produce less variability.

As expected, flops was far faster for the vfp code run on the N800 and slightly
faster for the softvfp code run on the N800 compared with the 770 (due to
processor speed difference).

The whetstone results were a little surprising, in that the vfp code wasn't
orders of magnitude faster than the softvfp code as expected, however this is
probably (as a guess) caused by libm not being compiled for vfp.

The whetstone tests are also rather variable, again due to the relatively small
number of iterations.

Paranoia states that both the softvfp and vfp systems produce correct IEEE 754
floating point results, though the results are different in some cases - see the
N800 results file and look at the end for the results from the hacked machar.c
(called a.vfp.out and a.softvfp.out).

Regards,


Simon