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In the following process state transition diagram for a uniprocessor system, assume that there are always some processes in the ready state:

Now consider the following statements:

  1. If a process makes a transition $D$, it would result in another process making transition $A$ immediately.
  2. A process $P_2$ in blocked state can make transition E while another process $P_1$ is in running state.
  3. The OS uses preemptive scheduling.
  4. The OS uses non-preemptive scheduling.

Which of the above statements are TRUE?

  1. I and II
  2. I and III
  3. II and III
  4. II and IV
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3 Answers

Best answer
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72 votes
  1. If a process makes a transition $D$, it would result in another process making transition $A$ immediately. - This is false. It is not said anywhere that one process terminates, another process immediately come into Ready state. It depends on availability of process to run & Long term Scheduler.
  2. A process $P2$ in blocked state can make transition $E$ while another process $P2$ is in running state. - This is correct. There is no dependency between running process & Process getting out of blocked state.
  3. The OS uses preemptive scheduling. :- This is true because we got transition $C$ from Running to Ready.
  4. The OS uses non-preemptive scheduling.Well as previous statement is true, this becomes false.

So answer is (C) II and III .

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23 votes

Answer is C :

The reason why option 1 may be false :If the process terminate ; then the Short time scheduler will bring immediately process from ready to run (not from new to ready ) . The process of bringing a process from new to ready is responsibility is job of Long Term Scheduler (which is called not so frequently as compared to Short Time Scheduler . Hence we named it Long Time Scheduler . the decision taken by it stays for a long time )

7 votes
7 votes
It is C.

The option I is not necessarily true.
Answer:

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