Fine-grain Parallelism with Minimal Hardware Support: A Compiler-Controlled Threaded Abstract Machine

Abstract

In this paper, we present a relatively primitive execution model for fine-grain parallelism, in which all synchronization, scheduling, and storage management is explicit and under compiler control. This is defined by a threaded abstract machine (TAM) with a multilevel scheduling hierarchy. Considerable temporal locality of logically related threads is demonstrated, providing an avenue for effective register use under quasidynamic scheduling. A prototype TAM instruction set, TLO, has been developed, along with a translator to a variety of existing sequential and parallel machines. Compilation of Id, an extended functional language requiring fine-grain synchronization, under this model yields performance approaching that of conventional languages on current uniprocessors. Measurements suggest that the net cost of synchronization on conventional multiprocessors can be reduced to within a small factor of that on machines with elaborate hardware support, such aa proposed dataflow architectures. This brings into question whether tolerance to latency and inexpensive synchronization require specific hardware support or merely an appropriate compilation strategy and program representation. © 1991, ACM. All rights reserved.