SURVEY & TUTORIAL SERIES Synchronization, Coherence, and Event Ordering in Multiprocessors

M ultiprocessors, especially those constructed of relatively low-cost microprocessors, offer a cost-effective solution to the continually increasing need for computing power and speed. These systems can be designed either to maximize the throughput of many jobs or to speed up the execution of a single job; they are respectively called throughput-oriented and speeduporiented multiprocessors. In the first type of system, jobs are distinct from each other and execute as if they were running on different uniprocessors. In the second type an application is partitioned into a set of cooperating processes, and these processes interact while executing concurrently on different processors. The partitioning of a job into cooperating processes is called multitasking’ * or multithreading. In both systems global resources must be managed correctly and efficiently by the operating system. The problems addressed in this article apply to both throughput-