Raspberry Pi, Soft-emu vs Hard float. [Updated]

I have had chance to build LuxRender on two distributions. The official Debian build, which uses software emulated floating point, and Raspbian, a build which uses hardware floating point and compiled to the specific ARM chip the Raspberry Pi has.

For numerically intensive functions, Raspbian should drastically improve performance, so in practice how does it fair with Lux?

I had two Raspberry Pis with Debian and one with Raspbian, in terms of peak samples per second, they break down as follows,
Debian 160 S/s
Raspbian 400 S/s
Raspbian 850 S/s in turbo mode…!!!!

This suggests around a 2.5x speed increase. After approximately one week of running for two of the Pi’s the total number of Samples per Pixel accumulated are as follows.
Debian 107 S/p
Raspbian  257 S/p

Which backs up the above giving about a 2.4x speed increase. Merging the two flm files together we get this result.

For comparison, using one thread of a 2.56 GHz Core 2 Duo on my mac we see about 16,000 S/s so the Raspberry Pi is indeed quite slow. But hey, anyone expecting it to be enormously speedy for stuff like this should have spent more time reading the FAQs.

A classroom of Raspberry Pi’s could make a nice lesson about cluster and parallel computing with LuxRender 🙂

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One Response to Raspberry Pi, Soft-emu vs Hard float. [Updated]

  1. Allister McCoy says:

    I’m nowhere near your level but i’ve been toying in some of the free tools and prefab content out there (i’m no good with modeling from scratch) So far i’ve been digging daz studio (http://www.daz3d.com/daz_studio). Mostly because its free and they have a ton of 3d content available. Now they have the nvidia iray renderer built in. Can’t wait to check it out.

    good work though. post again soon!

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