Process Synchronisation

Question

Semaphore is used to enforce Mutual Exclusion and Synchronization between processes interacting over shared data and variables. Which of the following statements is true about semaphores in this regard?

(a) The Operations SIGNAL(S) & WAIT(S) needs to be atomic.

(b) A process exiting the CS will call SIGNAL(S)

c) ‘Busy-Wait’ solutions to the Critical Section are typically implemented using machine instructions that execute in the Kernal mode

(d) all of the above

Answer 1

Only 1 needs to be true always. But "typically" in option 3 means it is also true. Busy-Wait can be done using Though there is no strict requirement to do a signal after CS, assuming it got a lock, the process has to release it. So, it also becomes true. So, I think D is the best choice.

Comments

@Arjun ,Sir Can you pls Explain.
How Statement c) is True
Isn't it TRUE only in case of TSL.

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what about peterson's solutions sir....