The GATE Grind

GATE 2020 CS – Question 22

Operating System · System Calls, Processes, Threads and IPC · 1 mark · Multiple choice

Consider the following statements about process state transitions for a system using preemptive scheduling.

I. A running process can move to ready state.

II. A ready process can move to running state.

III. A blocked process can move to running state.

IV. A blocked process can move to ready state.

Which of the above statements are TRUE?

  1. I, II, and III only
  2. II and III only
  3. I, II, and IV only
  4. I, II, III, and IV

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Show answer and explanation

Correct answer: (C) I, II, and IV only

Explanation

Running to ready (preemption), ready to running (dispatch) and blocked to ready (I/O completion) are valid transitions. Blocked to running is not, since a blocked process must go through ready first.