Empirical Evaluation of the CRAY-T3D: A Compiler Perspective

         Remzi H. Arpaci, David E. Culler, Arvind Krishnamurthy, 
              Steve G. Steinberg, and Katherine Yelick 

Most recent MPP systems employ a fast microprocessor surrounded by a
shell of communication and synchronization logic. The
CRAY-T3D  provides an elaborate shell to support global-memory access,
prefetch, atomic operations, barriers, and block transfers. We provide a
detailed empirical performance characterization of these primitives
using micro-benchmarks and evaluate their utility in compiling for a
parallel language. We have found that the raw performance of the machine
is quite impressive and the most effective forms of communication are
prefetch and write. Other shell provisions, such as the bulk transfer
engine and the external Annex register set, are cumbersome and of little
use. By evaluating the system in the context of a language
implementation, we shed light on important trade-offs and pitfalls in
the machine architecture.