Synchronization algorithms for shared-memory multiprocessors

A performance evaluation of the Symmetry multiprocessor system revealed that the synchronization mechanism did not perform well for highly contested locks, like those found in certain parallel applications. Several software synchronization mechanisms were developed and evaluated, using a hardware monitor, on the Symmetry multiprocessor system; the mechanisms were to reduce contention for the lock. The mechanisms remain valuable even when changes are made to the hardware synchronization mechanism to improve support for highly contested locks. The Symmetry architecture is described, and a number of lock algorithms and their use of hardware resources are examined. The performance of each lock is observed from the perspective of both the program itself and the total system performance.<>