GATE | Gate IT 2005 | Question 60
|Process||Priority||CPU time required|| Arrival time|
|P3||8 (lowest)||15 sec||00:00:00|
We have a choice of preemptive or non-preemptive scheduling. In preemptive scheduling, a late-arriving higher priority process can preempt a currently running process with lower priority. In non-preemptive scheduling, a late-arriving higher priority process must wait for the currently executing process to complete before it can be scheduled on the processor.
What are the turnaround times (time from arrival till completion) of P2 using preemptive and non-preemptive scheduling respectively.
(A) 30 sec, 30 sec
(B) 30 sec, 10 sec
(C) 42 sec, 42 sec
(D) 30 sec, 42 sec
Explanation: For Non preemptive scheduling
0 15 35 45
Turn Around Time= Completion Time – Arrival Time = 45 -3 = 42
For Preemptive scheduling
0 1 2 3 4 5 25 33 45
Turn Around Time= Completion Time – Arrival Time = 33 – 3 = 30
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