IEEE/ACM SC09 Aggregate.Org

This is the home page for our 16th major research exhibit at the IEEE/ACM Supercomputing conference. The exhibit is again under the title Aggregate.Org / University of Kentucky, the informal research consortium led by our KAOS (Compilers, Hardware Architectures, and Operating Systems) group here at the University of Kentucky's Department of Electrical and Computer Engineering.

A Maze Of Twisty Little Passages

Much like last year, the physically big thing in our exhibit this year is a technical demonstration consisting of a large wooden maze with four balls in it. Each of the colored balls has a different path to take (MIMD), yet it is perfectly feasible to get all the balls to their respective destinations by a series of tilts of the table (SIMD). Yes, you really can execute MIMD code on SIMD hardware with good efficiency... Click on the maze above for a ~50MB video showing the maze in action. Fundamentally, this is what our latest software does for GPUs (Graphics Processing Units). Specifically, it can take shared-memory MIMD code written in C and efficiently execute it on an NVIDIA CUDA GPU.

Why do this? GPUs thus far have not had stable, portable, programming support for general-purpose use, so there is virtually no code base for supercomputing applications. Our technology allows codes written for popular cluster and SMP target models to be used directly. We plan to support both C and Fortran with both shared memory and MPI message passing. The current shared memory model uses "parallel subscripting" in which a[||b] means a in processor b's memory; we initially assumed OpenMP would be the prefered model, but have had requests for Posix Threads. It is surprisingly easy to support dynamic thread creation, although there are performance issues involving memory bank conflicts in sharing the complete memory map.

How well does MIMD code perform? A lot better than it did last year. In fact, even the MIMD interpreter is fast enough to be usable for real applications.

Work Presented

The very wide range of topics emphasized in our exhibit is summarized in the following white papers, which are available as "print on demand" hardcopy from our research exhibit, booth 2273, at SC09:

Some related theses from our group:

Slow-Update Live View of our Exhibit

The following image was grabbed from a network camera with a 175-degree fisheye lens (door peephole) mounted on the top of our 16-foot-tall sign:

After-Show Stuff

Now that the show is over, here's a little about what we did and what we learned:

Some photos of our exhibit:

The booth overall (our tall backlit sign was visible from a good distance away)

Our environmentally-friendly print-on-demand handouts

The technical and overview slides (rear projection)

The maze

The student researchers in our booth this year

The Aggregate. The only thing set in stone is our name.