Much has been said about Cell’s presumed inability to texture map well. Given the small (256KB) local stores and DMA memory access, the SPEs were relegated by many to only handle nice streaming geometry type workloads. This seemed like an issue ripe for a little prototyping.

First, colleague Mark Nutter, implemented a software cache abstraction layer for the SPE giving us the ability to both hide the complexity of DMAs and benefit from transparent data reuse. Next, given the lessons learned from this paper, we tiled our textures, optimized our access patterns, and implemented several cache replacement policies. We then rewrote the shader in the Quaternion Julia Set Raytracer to add five cubemap texture lookup passes - 3 refraction lookups, a reflection lookup, plus a background lookup. These five texture lookups were then blended together with a fresnel calculation and modulated with the base lighting computation to form the final sample color.

The results were very pleasing.

Quicktime H.264 movie (16MB so be patient)

We found that even with small 4-way set associative software cache sizes (8 KB), miss rates for this renderer were a low 7% and hit access times were only 12 SPE cycles.

Using only seven 3.2 GHz SPEs we were able to raytrace 15 frames per second with a frame resolution of 1024×1024. The texture buffer held a cubemap with 1024×1024x16 bit texel faces resulting in a 12.5 MB texture buffer in XDR system memory. The performance penalty for using the five pass texture shader vs the lighting only shader was just 13%.

Our miss handler was implemented as a blocking function and we still have ideas pending to further reduce the 12 cycle software cache hit access time so we believe the 13% performance gap between the two shaders will continue to close.

IBM is at the Game Developers Conference this week. Come by and see us at booth #1230.
One of the things we are showing is a demo of the RapidMind Development Platform and Cell BE. From the RapidMind handout available at the booth:
“The RapidMind Development Platform allows developers to use standard C++ programming to easily create applications targeted for high performance processors including the Cell BE, GPUs and multi-core CPUs. In the case of the Cell BE, the RapidMind platform distributes processing across the SPEs without any explicit reference by the developer to the Cell BE. The platform provides a simple computational model that can be targeted by programmers and then maps this model onto any available computational resources in a system. Code can be written once then run in parallel on any of the processors that RapidMind supports.
What you will see at the demo: To demonstrate the performance acceleration available on the Cell BE processor when using the Rapid development Platform, RapidMind has created a world in which the behaviors of thousands of interacting characters are simulated.
In the demonstration (photo below) the Simulation Application is built in C++ using the RapidMind Development platform. RapidMind in turn leverages the power of two Cell BE processors on an IBM Cell blade to perform the simulation caculations. The state of each character (in this case chickens!) is streamed to the Visualization Application where RapidMind is used to map the state of each character onto visualization and to implement the shaders on the GPU.”

Among the executives at the booth are:

IBM: Hina Shah, Director, Cell Ecosystem & Solutions Development, Bruce D’Amora, Cell Digital Media Solutions Architect, Tanaz Sowdagar Marketing Manager Emerging Technologies, and Michael PerroneIBM Research Manager, Cell Applications Group, IBM Master Inventor
RapidMind: Ray DePaul, President & CEO, Stefanus Du Toit, Vice President, Development, Michael McCool, Chief Scientist, and Matthew Monteyne, Vice President Sales and Marketing.

Visit RapidMind at: http://www.rapidmind.net

Tags: Game Developers Conference , IBM , RapidMind, GDC

Let’s face it, with deadlines constantly approaching and crunch time becoming the industry standard, who has time to think about new and creative technology? But we all know that gamers expect new and creative more than anyone and Technology is at the very heart of this industry and touches upon the every day life of a game developer. From the “expected” to the “break through”, technology is what keeps this industry moving forward. That’s where we come in.

Under the “expected” technology category, I would include the better, faster, cheaper, we’re talking about the tools and systems that are the developer’s drawing board. They enable better collaboration, more asset reuse, faster and better performing systems etc. Many vendors, including IBM, play this space continuously coming out with new products that offer some improvements in clock speeds, or enanced I/O,etc.

The “breakthrough” category is the unexpected, these are technologies that disrupt the industry and change its course. Getting there takes dedicated research and a bit of genius powder. Very few vendors have the dedication and resources to uncover these breakthrough technologies, but I’m proud to say I work for one that does. Anyone in the industry knows by now that IBM designed processors will be at the heart of the major next generation game consoles. What you may not know, is that it’s taken close to a decade of research teams across the globe to develop the multithreaded processing technology.

These researches have lead the writing the IBM Systems Journal games issue. They’ve dedicated a good portion of their lives to this industry, and now they want to know what you think. Other breakthrough technologies that our researchers have tackled include Grid Architecture, which can expand the capability and profitability of online games, Business Integration technologies which enable new revenue streams for the industry, a much needed breath of air, and technologies that allow game companies to take community relations to a new level.

There’s an army or researchers at IBM labs across the world waiting to hear from you.

What did you think about the IBM Systems Journal?
Did you find it practical?
What was your favorite paper and why?
What do you expect to see from these researchers in the future?

If you’re more into f2f conversations, that’s cool too. A few of our researchers will join us at GDC on Wednesday the 22nd 4:00-5:00 pm at the IBM booth #1230. That’s right before booth crawl, so come wet your appetites and be one of the first 100 to get a free copy of the IBM Systems Journal.

Access the IBM Systems Journal Online (it’s free!)
http://www.research.ibm.com/journal/sj/