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Interactive Ray-tracer (iRT) Available for Download
We have now released a standalone version of the iRT for the Cell processor. The downloadable Linux binary runs on both the Sony Playstation3 (PS3) and the IBM QS20 blade.
http://www.alphaworks.ibm.com/tech/irt
This demonstration program shows both the ray-tracing potential of the Cell processor and the scalability of code written using the Cell SDK. Under Linux, the PS3 only has access to 6 of Cells 8 SPEs and has no access to the RSX graphics processing unit. Despite this the iRT can software ray-trace a 333,000 triangle car at interactive frame rates and can spin the 69,000 triangle Stanford bunny around in 720p at better than 40 frames per second. The iRT is also highly scalable, the IBM QS20 blade runs 2.5 time faster than the Linux PS3 and performance continues to scale linearly as additional QS20 blades are added.
On the alphaWorks site you will find the demonstration program plus two data sets, have fun!
Hi Barry
I ran iRT on my PS3 - very impressive. One thing that has me curious is that after spinning around both the Ferrari and the bunny for some time, I didn’t hear any of my PS3’s fans being called into duty. Stanford’s Folding@Home program, on the other hand, has the fans whirring within minutes or seconds. Does this mean that much of the Cell is idle during iRT rendering? I suppose one difference between the two programs is that Folding@Home drives both the Cell and the RSX at the same time (the RSX purely for the GUI I believe), which would generate more heat in total. But even with the very minimal Folding@Home screensaver active the fans spin on, suggesting that the Cell by itself is generating enough heat to cause this.
Another I noticed is that Linux reports that the PPE is 100% utilised (both virtual CPUs) during iRT rendering - can the PPE be a bottleneck even in floating-point arithmetic dominated application such as raytracing?
Thanks Turton,
If you look at the cooling system inside the PS3 you will notice that considerably more head sink/pipe was dedicated to the GPU than to Cell. So yes Folding@Home is using the GPU and therefore consumes more power than the iRT which only uses Cell. The PPE is at 100% during iRT execution because we have the CPU hot polling for SPE completion which provides us the best response time.