Difference Between Mutex and Binary Semaphore

[aurobind]

Hi,
Please tell me the differences between mutex and binary semaphores.
If possible, pls give the scenarios where a mutex and binary semaphore are used.
Thanks

[vikas]

hmm ... kind of offtopic ( try to search 4 it in a OS book )

[rohitd]

accocrding to me a mutex is a binary lock which can be acquired only once , it has the capability to handle the Priority inversion, while semaphore may be of incrementng or decrimenting and ca be acuired by more than 2 task at the same time while mutex cant be taken by more than 2 tasks
rohitd

[saurabhg84]

Its hard to figure out the difference between mutex and a binary semaphore till you get into the implementation details of both these.

Basically, a mutex attribute (structure) will have a field called ownership information, i.e.: the PID (process ID) of the process which is waiting on it, whereas binary semaphore implementation lacks ownership information.

This means that if there are 2 processes 'A' & 'B' sharing a mutex and if 'A' locks (waits on) the mutex, only A will be able to release the mutex, whereas if it would have been a binary semaphore, even process 'B' can accidentally release (signal) the mutex.

Apart from this, mutex is heavy weight and binary semaphore is light weight (speaking in UNIX lingo)...