Multi-core processors have been in the consumer market for several years now. However, despite having access to CPUs with two, three, four, and more cores, there are still relatively few applications available that can take advantage of multiple cores. Intel is hoping to change that and is urging developers of software to think parallel.
Intel director and chief evangelist for software development products talked about thinking parallel in a keynote speech he delivered at the SD West conference recently. James Reinders said, "One of the phrases I've used in some talks is, it's time for us as software developers to really figure out how to think parallel." He also says that the developer who doesn’t think parallel will see their career options limited.
Reinders gave the attendees eight rules for thinking parallel from a paper he published in 2007 reports ComputerWorld. The eight rules include -- Think parallel; program using abstraction; program tasks, not threads; design with the option of turning off concurrency; avoid locks when possible; use tools and libraries designed to help with concurrency; use scalable memory; and design to scale through increased workloads.
He says that after half a decade of shipping multi-core CPUs, Intel is still struggling with how to use the available cores. The chipmaker is under increasing pressure from NVIDIA who is leveraging a network of developers to program parallel applications to run on its family of GPUs. NVIDIA and Intel are embroiled in a battle to determine if the GPU or CPU will be the heart of future computer systems.
Programming for processors with 16 or 32 cores takes a different approach according to Reinders. He said, "It's very important to make sure, if at all possible, that your program can run in a single thread with concurrency off. You shouldn't design your program so it has to have parallelism. It makes it much more difficult to debug."
Reinders talked about the Intel Parallel Studio tool kit in the speech, a tool kit for developing parallel applications in C/C++, which is currently in its beta release. Reinders added, "The idea here [with] this project was to add parallelism support to [Microsoft's] Visual Studio in a big way."
Intel says that it plans to offer the parallel development kit to Linux programmers this year or early next year. The CPU Reinders is talking about when he says many-core is the Larrabee processor. Intel provided some details on Larrabee in August of 2008.
One of the key features of Larrabee is that it will be the heart of a line of discrete graphics cards, a market Intel has not participated in. Larrabee is said to contain ten of more cores inside the discrete package. If Larrabee comes to be in the form Intel talked about last year it will be competing directly against NVIDIA and ATI in the discrete graphics market.
NVIDIA is also rumored to be eyeing an entry into the x86 market as well. Larrabee will be programmable in the C/C++ languages, just as NVIDIA's GPUs are via the firms CUDA architecture.
quote: In a neat bending of technology to an unintended use, Daniel Pohl did one really cool thing, he used the same rays that you use for graphics to do collision detection. You cast rays out from the player and everything they hit may be an object. Since the math is being done already, collision detection, one of the harder problems with 3D games, is done for you. It isn't free, but considering how many millions of pixels there are on a screen, 1600*1200 would be almost 2 million pixels, a few hundred more per object is rounding error. You can do much more accurate collisions for every bullet and bit of debris spinning around, and do it right.
quote: Games: no way. You can use as many cores as you want for games. Most games being put out these days could be easily written to support thousands of cores for better performance. Games are extremely parallel in nature, and not just in graphics, but in mechanics as well.
quote: Now suppose it has a multi-threaded AI engine (let's say 4 threads). Whenever the time to render a screen comes up, a bunch of threads can compute the reaction of every character simultaneously, rather than one-by-one. So if you got 20 characters and need an average of 2 ms to determine the course of action per character, you use about 10 ms to compute that (20 characters x 2 ms each / 4 threads). That's parallel processing.In theory , the parallel engine could handle 80 characters while maintaining the same performance level of the serial engine.Of course, the multi-threaded solution has some overhead, the numbers are simplified. And I'm not even talking about the mess you can get into if a bug sneaks his way into your data synchronization mechanism. But you should get the idea why a multi-threaded game engine has more potential than a single-threaded one.
quote: I worked on Diablo II.
quote: We had 9 threads there a decade ago, and could have used far more if our target audience had more cores.