Assume that overlap of IO and processing can occur and only

Assume that overlap of I/O and processing can occur and only one device is used for I/O. Therefore, only on process can do I/O at a time. All I/O requests take 4 units of time. Maximum time allowed in CPU is 3. Process 1 stats at t = O 2 I/O 3 I/O 7 I/O 1 Process 2 starts at t = 1 6 I/O 5 I/O 4 I/O 3 I/O 2 I/O 1 Process 3 starts at t = 3 1 I/O 1 I/O 1 I/O 1 I/O 1 I/O 1 I/O 3 Process 4 starts at t = 4 6 1 1/O 1 I/O 3 I/O 4 I/O 7 Calculate the following: Average time of completion, CPU utilization, Context Switches.

Solution

here we are having time that i/o request time is 4units

and cpu can take a maximum time 3units to excute, so after cpu time, the process p1 stops its execution and goes to nest execution. here in p2 starts its execution, but the time difference between p2 & p3 is 2, so p2 completes its execution and goes to process p3 and so on.

At average time for completion is 12

CPU utilization is 3