ps3

People

Core Faculty

•Dana Fine, UMassD Math, MA
•Robert Fisher, UMassD Physics, MA
•J. P. Hsu, UMassD Physics, MA
•Gaurav Khanna, UMassD Physics, MA

Collaborative Faculty

•Martin Bojowald, Penn State, PA
•Lior Burko, UAlabama, AL
•Bruce Allen, AEI Hannover, Germany
•Scott Hughes, MIT, MA
•Jorge Pullin, Louisiana State, LA

Current Students

•Matthew Hogan, UMassD Physics, MA
•SungHoon Kim, UMassD Physics, MA
•Rakesh Ginjupalli, UMassD Physics, MA
•Sarah McLeod, UMassD Physics, MA
•Justin McKennon, UMassD ECE, MA
•Ian Nagle, UMassD Physics, MA

Past Students (Current Location)

•Pranesh Sundararajan, Finance
•Joshua Liberty, Univ. of Rhode Island
•Emanuel Simon, Univ. of Ulm, Germany
•Francis Boateng, UMass Lowell
•Subir Sabharwal, Columbia University
•Vishnu Paruchuri, Finance
•Jessica Rosen, Industry
•Peter Goetz, Univ. of Ulm, Germany
•Seth Connors, High-School Teacher
•Zhenhua Ning, Univ. of Illinois UC
•Nobuhiro Suzuki, Univ. of Rhode Island
•Mike O'Brien, Rutgers Univ.
•Matt Strafuss, MIT

PS3 Gravity Grid in the Media

This section is dedicated to the ongoing research projects of our group that involve supercomputing in Physics.

The Sony PlayStation 3 has a number of unique features that make it particularly suited for scientific computation. First, the PS3 is an open platform, which essentially means that one can run a different system software on it, for example PowerPC Linux. Next, it has a revolutionary processor called the Cell processor which was developed by Sony, IBM and Toshiba. This processor has a main CPU (called the PPE) and several (six (6) for the PS3) special compute engines (called SPEs) available for raw computation. Moreover, each SPE performs vector operations, which implies that they can compute on multiple data, in a single step (SIMD). Finally, its incredibly low cost make it very attractive as a scientific computing node i.e. part of a compute cluster. In fact, its highly plausible that the raw computing power-per-dollar that the PS3 offers, is significantly higher than anything else on the market today.

Thanks to a very generous, partial donation by Sony, we have a sixteen (16) PS3 cluster in our department, which we call PS3 Gravity Grid. Check out some pictures of the cluster here: 1) the PS3's arrive; 2) the rack arrives; 3) front view of the original cluster; 4) side view of the original cluster; 5) front view of the upgraded cluster; 6) side view of the upgraded cluster. For instructions on how this cluster was built, please visit our companion site: ps3cluster.org.

Projects

•Binary Black Hole Coalescence using Perturbation Theory (GK)
This project broadly deals with estimating properties of the gravitational waves produced by the merger of two black holes. Gravitational waves are “ripples” in space-time that travel at the speed of light. These were theoretically predicted by Einstein’s general relativity, but have never been directly observed. Currently, there is an extensive search being performed for these waves by the newly constructed NSF LIGO laboratory and various other such observatories in Europe and Asia. The ESA and NASA also have a mission planned in the near future -- the LISA mission -- that will also be attempting to detect these waves. To learn more about these waves and the recent attempts to observe them, please visit the LISA mission website.
The evolution computer code for the extreme-mass-ratio limit of this problem (commonly referred to as EMRI) is essentially an inhomogeneous wave-equation solver which includes a mathematically complicated source-term. The source-term describes how the smaller black hole (or star) generates gravitational waves as it moves in the space-time of the larger hole. Because of the computational complexity of the source-term, it is the most computationally intensive part of the whole evolution. On the PS3's Cell processor, it is precisely this part of the computation that is “farmed out” to the six (6) SPEs. This approach essentially eliminates the entire time spent on the source computation and yields a speed up of over a factor of six (6) over a PPE-only computation. It should be noted that the context of this computation is double-precision floating point operations. In single-precision, the speed-up is significantly higher. Furthermore, we distribute the entire computational domain across the sixteen (16) PS3s using MPI (message passing) parallelization. This enables each PS3 to work on its part of the domain and communicate the appropriate data to the others, as needed on-the-fly. Overall, the performance of our PS3 Gravity Grid compares to nearly 100 cores of high-end Intel Xeon processors or as many as 500 nodes of an IBM Blue Gene supercomputer. Here is a list of research articles published using results generated using this cluster: Phys. Rev. D78 064042 (2008); Class. Quant. Grav. 26 015014 (2009); PPAM (2009); PDCS (2009); IJMSSC (2009)
•HPL - Standard supercomputer cluster benchmark (GK)
This project is about performing a standard LINPACK cluster benchmark on our sixteen (16) PS3 cluster. This is the benchmark that is used by the top500.org site that lists the most powerful supercomputers in the world. We worked with IBM to port their QS22 Cell blade benchmark code to our PS3 cluster. The results? The PS3 Gravity Grid generates a total performance of 40 GFLOP/s (40 billion calculations per second). It should be noted that this benchmark was run in double-precision and because of the limited RAM on each PS3 we were only able to fit a matrix of size 10K on the entire cluster. The larger the problem size, the better the Cell's efficiency, therefore these testing conditions were far from optimal (unfortunately). We expect to be able to get much much better performance from the cluster if we had significantly more RAM available. Even with the 40 GFLOP/s, our PS3 cluster is very competitive (in terms of performance-per-dollar) with the low-cost compute clusters out there. And if one could take advantage of doing some of the computation in single-precision, the performance would jump several fold -- likely achieve nearly one-half a TFLOP/s (half a trillion calculations a second). The benchmark code with Cell specific patches is available here: HPL.
Questions? Feel free to contact Gaurav Khanna about this research and the PS3 Gravity Grid.