Lazy task creation: A technique for increasing the granularity of parallel programs. Technical report
Many parallel algorithms are naturally expressed at a fine level of granularity, often finer than a MIMD parallel system can exploit efficiently. Most builders of parallel systems have looked to either the programmer or a parallelizing compiler to increase the granularity of such algorithms. In this paper, the authors explore a third approach to the granularity problem by analyzing two strategies for combining parallel tasks dynamically at run-time. They reject the simpler load-based inlining method, where tasks are combined based on dynamic load level, in favor of the safer and more robust lazy task creation method, where tasks are created only retroactively as processing resources become available. These strategies grew out of work on Mul-T 17, an efficient parallel implementation of Scheme, but could be used with other languages as well. They describe our Mul-T implementations of lazy task creation for two contrasting machines, and present performance statistics which show the method's effectiveness. Lazy task creation allows efficient execution of naturally expressed algorithms of a substantially finer grain than possible with previous parallel Lisp systems.
- Research Organization:
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Lab. for Computer Science
- OSTI ID:
- 5306017
- Report Number(s):
- AD-A-237477/5/XAB; MIT/LCS/TM-449; CNN: N00014-87-K-0825
- Country of Publication:
- United States
- Language:
- English
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