This paper studies the problem of efficiently scheduling fully strict (i.e., well-structured) multithreaded computations on parallel computers. A popular and practical method of scheduling this kind of dynamic MIMD-style computation is "work stealing," in which processors needing work steal computational threads from other processors. In this paper, we give the first provably good work-stealing scheduler for multithreaded computations with dependencies. Specifically,

Abstract — Arguably, one of the biggest deterrants for software developers who might otherwise choose to write parallel code is that parallelism makes their lives more complicated. Perhaps the most basic problem inherent in the coordination of concurrent tasks is the enforcing of atomicity so that the partial results of one task do not inadvertently corrupt another task. Atomicity is typically enforced through locking protocols, but these protocols can introduce other complications, such as deadlock, unless restrictive methodologies in their use are adopted. We have recently begun a research project focusing on transactional memory [18] as an alternative mechanism for enforcing atomicity, since it allows the user to avoid many of the complications inherent in locking protocols. Rather than viewing transactions as infrequent occurrences in a program, as has generally been done in the past, we have adopted the point of view that all user code should execute in the context of some transaction. To make this viewpoint viable requires the development of two key technologies: effective hardware support for scalable transactional memory, and linguistic and compiler support. This paper describes our preliminary research results on making “transactions everywhere ” a practical reality. I.

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First of all, I would like to thank Prof. Dr. Claudia Leopold for giving me the opportunity to work in her group of “Programming Languages and Parallel Programming ” at University of Kassel and Prof. Dr. Emre Harmancı who accepted to be my supervisor. Prof. Leopold never let me alone even in the rest of my work in Turkey. Working at University of Kassel was a great experience for me. I feel fortunate to have helpful friends, Björn Knafla and Michael Süss who made my first time in Germany enjoyable. Thanks to Christiane Becker and Raffaele Biscosi for being so nice to me. I am grateful to Dr. Turgay Altılar who encouraged me for the presentations and helped me a lot. Special thanks to my parents who always supported me. December 2004 Ay¸se Beliz S¸enyüz iv TABLE OF CONTENTS ABBREVIATIONS viii