SCHEDULING

Question

i am getting answer as 6....to calculate waiting time i have removed CPU time used by the process (BT) from total time spend inside(TAT)....not included I/O time(i think I/O is also included in waiting time)..is it correct?

Three processors P,Q,R are started at times 0 ,2 ,3 milliseconds respectively. Each of the process performs a computation that required T_C1 CPU milliseconds then initiates a single I/O operation that lasts for T_IO milliseconds and at the last it again performs a computation that required T_C2 CPU milliseconds. It is assumed that the processes execute has sufficient number of I/O devices and the OS of the computer assigns different I/O devices to each process . Also scheduling overhead of the OS is negligible. The processes have the following characteristics :

Process	Arrival Time	Priority	TC1	TIO	TC2
P	0	2	1	5	3
Q	2	3(L)	3	3	1
R	3	1(H)	2	3	1

What is the average waiting time (in milliseconds) ?

Comments

I think $6$ is correct.

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@mcjoshi bro....u r finding waiting time by subtracting only BT isnt it?
I/O is already included in waiting time...just confirm this

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yes...it is priority scheduling :)

Answer 1

Answer is 6. here's the explanation