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

[From: Kalle Vahlman]

2007/2/12, Kalle Vahlman <kalle.vahlman at gmail.com>:
> 2007/2/12, Simon Pickering <S.G.Pickering at bath.ac.uk>:
> >
> > > 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.
>
> Indeed, I ran these with a vfp libm and the results speak for themselves:
>
> ./whetstone.vfp.O0.out
>
> Loops: 1000, Iterations: 1, Duration: 7 sec.
> C Converted Double Precision Whetstones: 14.3 MIPS
> ---
> ./whetstone.vfp.O1.out
>
> Loops: 1000, Iterations: 1, Duration: 3 sec.
> C Converted Double Precision Whetstones: 33.3 MIPS
> ---
> ./whetstone.vfp.O2.out
>
> Loops: 1000, Iterations: 1, Duration: 2 sec.
> C Converted Double Precision Whetstones: 50.0 MIPS
> ---
> ./whetstone.vfp.O3.out
>
> Loops: 1000, Iterations: 1, Duration: 2 sec.
> C Converted Double Precision Whetstones: 50.0 MIPS
> ---
> ./whetstone.vfp.Os.out
>
> Loops: 1000, Iterations: 1, Duration: 3 sec.
> C Converted Double Precision Whetstones: 33.3 MIPS
> ---

Duh, I was looking at the wrong results from
http://people.bath.ac.uk/enpsgp/benchmarks/N800-fp-tests.txt, my
numbers match those in there even with vfp libm...

-- 
Kalle Vahlman, zuh at iki.fi
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