Question

About n processes are time-sharing the CPU, each requiring T ms of CPU time to complete. The context switching overhead is S ms. (a) What should be the quantum size Q such that the gap between the end of one quantum and the start of the next quantum of any process does not exceed M ms? (b) For n = 5, S = 10, and M = 450, M = 90, M = 50, determine: The corresponding values of Q The percentage of CPU time wasted on context switching

Answer 1

Answer:

(a) Q = (M-(1-n)S)/n

(b)    

When M = 450,

       Q = 82

       % CPU time wasted = 8.889%

When M = 90,

       Q = 10

       % CPU time wasted = 44.44%

When M = 50,

       Q = 2

       % CPU time wasted = 80%

Explanation:

Given  Data:

n = process

T = ms time

Context switch time overhead = S

and M is total overhead

See attached file for the calculation.