Active Messages: A Mechanism for Integrated Communication and Computation

The design challenge for large-scale multiprocessors is (1) to minimize communication overhead, (2) allow communication to overlap computation, and (3) coordinate the two without sacrificing processor cost/performance. We show that existing message passing multiprocessors have unnecessarily high communication costs. Research prototypes of message driven machines demonstrate low communication overhead, but poor processor cost/performance. We introduce a simple communication mechanism, Active Messages, show that it is intrinsic to both architectures, allows cost effective use of the hardware, and offers tremendous flexibility. Implementations on nCUBE/2 and CM-5 are described and evaluated using a split-phase shared-memory extension to C, Split-C. We further show that active messages are sufficient to implement the dynamically scheduled languages for which message driven machines were designed. With this mechanism, latency tolerance becomes a programming/compilingconcern. Hardware suppo...

• Type: Conference
• Year: 1998
• Where: ISCA
• Authors: Thorsten von Eicken, David E. Culler, Seth Copen Goldstein, Klaus E. Schauser
• Keywords: Active Messages, Communication, Hardware, ISCA 1998, Message Driven Machines