Network interface for a data driven network of workstations (D2 NOW)

Abstract

This paper presents the network interface for the Data Driven Network Of Workstations (DzNOW), a multithreaded architecture that uses the decoupled data driven model of execution. D2NOW is built using commodity workstations. The support for the data driven synchronization of threads, is provided by the Thread Synchronization Unit (TSU). The TSU is attached in the COAST (Cache On A STick) L2 Cache slot of Pentium workstations and thus it has an implicit interface, using snooping, to the Pentium microprocessor. Workstations are connected via a Telegraphos interconnection network. The DZNOW supports fine grain threads and thus is coupled to a fine grain network, the Telegraphos, which is a high throughput ATM-like network. Telegraphos uses short packets and guarantees no packet-drop, which is a must for fine grain data-driven computation. The Network Interface Unit (NIU) is incorporated on the TSU board. The NIU is implemented using two FPGAs and it has very low hardware overhead. Remote writes are carried out in less than a microsecond.