In previously published work, PNNL computational scientist Jarek Nieplocha used a predecessor of the Cray XMT to run typical software programs that help operators keep the power grid running smoothly. Adapted to the advanced hardware, these programs ran 10 times faster on the multithreaded machine. "That was the best speed ever reported. We're getting closer to being able to track the grid in real time," said Nieplocha.
In biology, another complex web is woven by genes (or their protein products) working together inside people's cells. "We have discovered genes implicated in breast cancer using a massively multithreaded algorithm on the Cray XMT," said Georgia Tech computational scientist and engineer David A. Bader. "It's like finding a needle in a haystack. The algorithm searches for genes whose removal quickly causes networks and pathways in the cell to breakdown."
The processors and computer memory in the advanced computers interact in a novel way. In traditional supercomputers, each processing chip gets a dollop of memory to use for its computations. To perform a calculation, the chip dips into the memory, does its work, then accesses the memory again for its next calculation, like an elephant dipping its trunk into a bag of peanuts and eating them one at a time. Each processor-memory unit is linked together over a network, and performance improvements come with more and faster processors and sleek network connections.
The Cray XMT multithreaded system lumps all the memory together, and the processors freely access the much larger memory pool. But like an elephant with many trunks, each processor has multiple threads: it dips into memory with one thread, and while that thread is performing the calculation at hand, another thread goes into the memory, and another.
By the time all the threads have dipped, the original thread has finished its calculation and is r
|Contact: Mary Beckman|
DOE/Pacific Northwest National Laboratory