Average Waiting Time

Question

Calculate Average Waiting Time

Comments

Scheduling Policy ?

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FCFS

Answer 1

Avg WT = 19.5

Avg TAT = 28.25 Plz check the ans

 

Comments

WT = TAT - EXTime  // we have to take only processor time

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No it's WT = TAT - (CPU Time + I/O Time)

https://gateoverflow.in/75241/scheduling

 

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Waiting Tine is the Time for which the process waits for the CPU to be available.

Consider a process A having (EX1 = 2 ......IO = 6..... EX2=2) arrives at time 0.  it will first execute for 2 then goes for I/O for 6 .....Again execute for 2 .  TAT = 10   WT would be 6  .

It doesn't matter what a process does if it has not been assigned CPU after it  enters Ready queue Everything is counted as WT ( ie any I/O performed in bw is already considered in WT ) and need not be explicitly subtracted from TAT