00000cab a22000003a 4500 UP-99796217608727536 Buklod 20231007234724.0 m |o d | ta 090226s xx d | ||r ||||| || (iLib)UPD-00077096450 DENGII eng Dwork, Cynthia Contention in shared memory algorithms. pp. 779-805 Most complexity measures for concurrent algorithms for asynchronous shared-memory architectures focus on process steps and memory consumption. In practice, however, performance of multiprocessor algorithms is heavily influenced by contention, the extent to which processess access the same location at the same time. Nevertheless, even though contention is one of the principal considerations affecting the performance of real algorithms on real multiprocessors, there are no formal tools for analyzing the contention of asynchronous shared-memory algorithms.This paper introduces the first formal complexity model for contention in shared-memory multiprocessors. We focus on the standard multiprocessor architecture in which n asynchronous processes communicate by applying read, write, and read-modify-write operations to a shared memory. To illustrate the utility of our model, we use it to derive two kinds of results: (1) lower bounds on contention for well-known basic problems such as agreement and mutual exclusion, and (2) trade-offs between the length of the critical path (maximal number of accesses to shared variables performed by a single process in executing the algorithm) and contention for these algorithms. Furthermore, we give the first formal contention analysis of a variety of counting networks, a class of concurrent data structures inplementing shared counters. Experiments indicate that certain counting networks outperform conventional single-variable counters at high levels of contention. Our analysis provides the first formal model explaining this phenomenon. Theory of computation. Computation by abstract devices. Complexity measures and classes. Relations among complexity classes. Computer systems organization. Processor architectures. Analysis of algorithms and problem complexity. Algorithms. Performance. Theory. Journal of the ACM 44, 6 (1997). FO UPD DENG-II Article