Question

Question

Suppose in a system, processes arrive at an average rate of 6 per minute.On average each process takes 8 seconds of service time. Estimate the % of time CPU is idle in a single processor system is ______

Comments

consider process coming at 0,10,20,30,40,50 seconds thus 6 process

1st process will be done servicing at 8th second ,so CPU has to wait until 10 th second until 2nd process arrives

i.e CPU waits for 2 seconds ,this will happen for all 6 processes and again after 6th process ,CPU will wait for 1st process

6*2=12 seconds wait(IDLE)=(12/60*)100=20%

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see question ask , unutilized time ;

6 process come in 1 minuts = in one 60 seconds 6 process executes only

now it says each take 8 sec to execute = so total time for execution = 6 $\times$8 = 48

unutilized time = ideal time = 60 - 48 = 12 sec

in % = $\left ( \frac{12}{60} \right )\times100 = 20$%

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Got it, thanks all.