GATE - 2020 | OS | Consider the following statements about process state transitions for a system

GATE - 2020 [Operating System]

Question:

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 ready 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?

A	II and III only
B	I, II and III only
C	I, II, III and IV
D	I, II and IV only

      

Solution:

Option D is Correct

STATEMENT I - TRUE

A process can move from running state to ready state on interrupt or when priority expires, that is, when it is pre-empted.

STATEMENT II - TRUE

A ready process moves to running process when it is dispatched.

STATEMENT III - FALSE

A blocked process that is in waiting state can never move directly to running state. It must go to ready queue first.

STATEMENT IV - TRUE

A blocked or waiting process can move to ready state.

Important Point:

The transition from running to ready state is possible only in pre-emptive scheduling. It cannot happen in non pre-emptive scheduling.

 

Thank You