Abstract
One approach for building the next generation of parallel computers
is based on large aggregates of multiprocessor chips with support
for hardware multithreading. An initial design for IBM's Blue
Gene/C project exemplifies this approach. Such a machine might
consist of a million processors, and is characterized by a low
memory-to-processor ratio. To study alternate programming models
for such a machine before it is built, we have developed an
emulator that allows million-processor programs to be run on
conventional parallel machines with hundreds of processors. Here we
present the implementation of a parallel object model based on
Charm++ as a candidate programming model. Although the ``ideal''
programming model for such machines is a matter of continuing
research, we believe that parallel objects represent a good
starting point. This paper reviews the target architecture,
presents the programming model, and describes the emulator
implementation. Case studies of simple applications written using
the emulator are also discussed.