I have 3 processes P1,P2,P3 having gantt chart as follows =>

enter image description here

Now, CPU remains idle in 0 - 2 sec and 44 - 47 seconds as I/O is taking place.

Does, this affect throughput as 3 processes can be completed in total 47 sec .

Hence, throughput = 3 / 47 .

Is this correct or am i missing something ?


You are correct!

According to the defenition Throughput (in case of scheduling in OS) is :

Number of processes that can be completed in a unit of time.

The process can use both the CPU or the I/O operations. So the I/O time and idle times and CPU time are calculated in throughput.

Note: CPU idle time is not calculated when you want to have the Utilization of the CPU. So in your case CPU Utilization is 42/47.

  • $\begingroup$ Number of processes that are completed , means i/o and cpu both should be completed right ? $\endgroup$ – Garrick Oct 6 '16 at 18:44
  • 1
    $\begingroup$ @Willturner yes because a process may use both CPU and I/O! $\endgroup$ – Peyman.H Oct 6 '16 at 19:03

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