Are mutexes really slower?

Question

I have read so many times, here and everywhere on the net, that mutexes are slower than critical section/semaphores/insert-your-preferred-synchronisation-method-here. but i

Answer 1

I don't believe that any of the answers hit on the key point of why they are different.

Mutexes are at operating system level. A named mutex exists and is accessible from ANY process in the operating system (provided its ACL allows access from all).

Critical sections are faster as they don't require the system call into kernel mode, however they will only work WITHIN a process, you cannot lock more than one process using a critical section. So depending on what you are trying to achieve and what your software design looks like, you should choose the most appropriate tool for the job.

I'll additionally point out to you that Semaphores are separate to mutex/critical sections, because of their count. Semaphores can be used to control multiple concurrent access to a resource, where as a mutex/critical section is either being accessed or not being accessed.