Exploring parallelism on pure functional languages with ACQuA

Abstract

Moore’s law reaching its physical limitations has pushed the industry to produce multicore processors. However, programming those processors with an imperative language is not easy since it requires developers to create and synchronize threads. A pure functional language is an adequate tool for this task both from the architectural point of view and from the developer’s. We will show that an architecture can benefit from the implicit parallelism present on functional programs and from the lack of side effects making it easier to parallelize. The developer benefits from functional languages from the superior expressiveness of the language to avoid bugs. In this dissertation, we present the ACQuA architecture, a multicore accelerator created to explore parallelism available in function calls from a pure functional program. ACQuA uses hardware support and a specificallytailored memory organization to minimize the overheads of scheduling, communication, and synchronization. Function calls are placed into a queue and are scheduled to different processing units. The processing units are interconnected and exchange results from function applications. In this work we defined a high level model of the accelerator and how to compile a functional program to it. We also simulated the accelerator and evaluated results, such as speedup, memory usage, and communication overhead of the proposed architecture. We defined the necessary traits of a program to achieve a good speedup on the architecture. On the ideal use case, we can increase the speed up at the same rate we increase the number of processing units in the architecture.