Berkeley Univ. CS Dept.


TI Active Messages: A Mechanism for Integrated Communication and
Computation 

OR UCB 

LT CSD 92675 

AU Thorsten von Eicken 

AU David E. Culler 

AU Seth Copen Goldstein 

AU Klaus Erik Schauser 

AB 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 costperformance. 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 costperformance. 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 0ube and
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 programmingcompiling concern.
Hardware support for active messages is desirable and we outline
a ran8e of enhancements to mainstream pressors.