Let P0 And P1 are two processes,each accessing two binary semaphore s and q set to value 1:

Question

P0

wait(s); wait(q);

Signal (s); signal(q);...

P1[

wait(q);wait(s);}

signal(q);signal(s);....

whether progress is guarnteed or not ???

Answer 1

Progress is not guaranteed I think bcz P0 will do down operation on s and q,so when  P0 is in critical section for a very long time P1 have to wait for arbitrary time until P0 releases s and q.When a process is stopping other process from executing then we say there is no progress.correct me if I'm wrong..

Comments

Nopes. Explanation is wrong. Progress is not guaranteed when a process in remainder section (not CS) stops other process from entering CS or if no process can enter CS in a definite time. Here, there is a chance that deadlock can happen and hence no process will be entering CS indefinitely and this causes no progress.

---

thanks sir :)

---

but sir if P1 is not interested in going to CS why will it take down on s and and stops P2

Answer 2

Progress is not guarnteed, consider the case when both processes arrive simultaneously.P1 sets S to 0 and P2 sets to 0.Hence further they enter deadlock situation hence no process gets to use critical section.

correct me if I am wrong.