In this paper we make a comparative study of the overheads of locks and STM by taking different practical synchronization problems as examples to understand why the performance of STM is worse than that of locks. Overhead is the combination of excess or indirect computation time, memory, bandwidth, or other resources that are required to perform a specific task. While executing parallel programs whenever any lock or STM function is called it takes some time and also occupies some space. The total time taken by all the lock or STM calls of the program is the total lock or STM time overhead of that program. The total space occupied by all the lock or STM calls of the program is the total lock or STM space overhead of that program. The flexible approach is an approach of programming with STM by which STM has been made more user-friendly and by which execution time of STM has been reduced. We make a study of the overheads of the flexible approach also. We found that the time and space overheads of STM are higher than that of locks. The time and space overheads of the Flexible Approach were less than those of STM but higher than those of locks.

Multiprocessing, Parallel Processing, Locks, Software Transactional Memory, Overheads

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