Question 3587 – UGC NET CS 2016 Aug- paper-2

Consider three CPU intensive processes P1 , P2 , P3 which require 20, 10 and 30 units of time, arrive at times 1, 3 and 7 respectively. Suppose operating system is implementing Shortest Remaining Time first (preemptive scheduling) algorithm, then _____ context switches are required (suppose context switch at the beginning of Ready queue and at the end of Ready queue are not counted).

Correct Answer: A

P​ ₁​ → P_{​ 2}​ is one switch
P​ ₂​ → P_{​ 1}​ is 2nd switch
P​ ₃​ → P_{​ 3​} is 3rd switch