An analysis of dag-consistent distributed shared-memory algorithms

Abstract

In this paper, we analyze the performance of parallel mttltithreaded algorithms that use dag-consistent distributed shared memory. Specifically, we analyze execution time, page faults, and space requirements for multithreaded algorithms executed by a workstealing thread scheduler and the BACKER coherence algorithm for maintaining dag consistency. We prove that if the accesses to the backing store are random and independent (the BACKER algorithm actually uses hashing), then the expected execution time of a "fully strict" multithreaded computation on P processors, each with an LRU cache of C pages, is O(T1 (C)/P+ ntC7"), where T1(C) is the total work of the computation including page faults, L is its criticalpath length excluding page faults, and m is the minimum page transfer time. As a corollary to this theorem, we show that the expected number of page faults incurred by a computation executed on P processors, each with an LRU cache of C pages, is F] (C) + O(CPT~), where Fl (C) is the number of serial page faults. Finally, we give simple bounds on the number of page faults and the space requirements for "regular" divide-and-conquer algorithms.