An architecture for optimal all-to-all personalized communication
SPAA '94 Proceedings of the sixth annual ACM symposium on Parallel algorithms and architectures
Decoupling synchronization and data transfer in message passing systems of parallel computers
ICS '95 Proceedings of the 9th international conference on Supercomputing
Practical parallel algorithms for personalized communication and integer sorting
Journal of Experimental Algorithmics (JEA)
Toward Optimal Complete Exchange on Wormhole-Routed Tori
IEEE Transactions on Computers
Communication patterns and models in prism: a spectral element-Fourier parallel Navier-Stokes solver
Supercomputing '96 Proceedings of the 1996 ACM/IEEE conference on Supercomputing
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In all-to-all personalized communication (AAPC), every node of a parallel system sends a potentially unique packet to every other node. AAPC is an important primitive operation for modern parallel compilers, since it is used to redistribute data structures during parallel computations. As an extremely dense communication pattern, AAPC causes congestion in many types of networks and therefore executes very poorly on general purpose, asynchronous message passing routers. We present and evaluate a network architecture that executes all-to-all communication optimally on a two-dimensional torus. The router combines optimal partitions of the AAPC step with a self-synchronizing switching mechanism integrated into a conventional wormhole router. Optimality is achieved by routing along shortest paths while fully utilizing all links. A simple hardware addition for synchronized message switching can guarantee optimal AAPC routing in many existing network architectures. The flexible communication agent of the iWarp VLSI component allowed us to implement an efficient prototype for the evaluation of the hardware complexity as well as possible software overheads. The measured performance on an 8 x 8 torus exceeded 2 GigaBytes/sec or 80% of the limit set by the raw speed of the interconnects. We make a quantitative comparison of the AAPC router with a conventional message passing system. The potential gain of such a router for larger parallel programs is illustrated with the example of a two-dimensional Fast Fourier Transform.