LIBRARIES Optimizing the UPC Communication Run-Time Library

This paper describes the design of a basic communication run-time library for the UPC parallel language and DEC's Memory Channel hardware. Also described is an implemen-tation of Cachet, an adaptive cache coherence protocol for distributed systems, which was added to the basic communication layer to even further boost performance. The implemen-tation of two Cachet micro-protocols: Cachet-Base and Cachet-WriterPush are described. The Cachet cache coherence scheme was implemented entirely in software on Alpha work-stations. The results of benchmarks running on the basic communication layer with and without Cachet are presented. These experiments show that the communication optimiza-tion can provide a performance improvement of up to an order of magnitude over th