Semaphore and mutex, which is faster?

Question

If you are considering binary semaphore and mutex, which one is faster? I mean, it takes fewer instructions. What additional data does the mutex support compared to the semaphore?

Answer 1

It depends on the implementation, but you will probably find that the mutex is implemented a little faster. Mutexes are usually implemented using a test and a set, while semaphores are often implemented using a test and an increment, or as a mutex protecting a variable that increases.

I would suggest using a mutex in most cases, but not because of speed; simply because code written using mutexes is easier to understand because semantics are less complex.