stream benchmarking on RPi

[Warner Losh]

On Sep 5, 2013, at 2:02 PM, Jia-Shiun Li wrote:

> Hi all,
> 
> just did a brief test using stream, the memory bandwidth benchmark, on
> RPi with Raspbian and FreeBSD. Share these info to see if someone
> might think of it useful.
> 
> FreeBSD is faster at copying. I guess that must be attributed to
> recent VM and/or superpage commits. I remembered it to be under
> 300MB/s months before. On the other hand, scale, add, and triad are
> significantly slower. Anyone have clues or any wild guesses?

Soft float?

Warner

> Below the only compiler option given for cc/gcc is -O3.
> 
> Raspbian 2013-07-26 (lk 3.6, gcc 4.6):
> -------------------------------------------------------------
> Function    Best Rate MB/s  Avg time     Min time     Max time
> Copy:             257.3     0.062703     0.062189     0.063824
> Scale:            205.1     0.079135     0.077993     0.082000
> Add:              284.1     0.085253     0.084480     0.088597
> Triad:            274.3     0.087799     0.087501     0.087940
> -------------------------------------------------------------
> 
> FreeBSD 10.0-CURRENT r255120 w/ cc(clang):
> -------------------------------------------------------------
> Function    Best Rate MB/s  Avg time     Min time     Max time
> Copy:             365.5     0.045321     0.043779     0.052929
> Scale:             31.2     0.531028     0.513082     0.550906
> Add:               68.5     0.367295     0.350467     0.391310
> Triad:             26.9     0.902672     0.893316     0.908908
> -------------------------------------------------------------
> 
> FreeBSD 10.0-CURRENT r255120 w/ gcc (4.2.1):
> -------------------------------------------------------------
> Function    Best Rate MB/s  Avg time     Min time     Max time
> Copy:             264.6     0.063977     0.060470     0.081000
> Scale:             31.0     0.535830     0.516093     0.551035
> Add:               46.7     0.534768     0.514323     0.553834
> Triad:             23.1     1.047644     1.038968     1.066887
> -------------------------------------------------------------
> 
> 
> Jia-Shiun.
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