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Part $1$: Scheduling $(10$ points$)$

$($a$)$ A FIFO scheduler receives three jobs $($A$,$ B$,$ C$),$ each with arrival time of $0$ second. Process A has run time of $60$

second, whereas Process B and C have runtime of $10$ second. What is the average turnaround time? $(5$ points$)$

Average Turnaround time $($in seconds$)$: $70$sec $($assuming A started first$)$

If you made an assumption that B or C started first, and the calculation was

correct, you were given full points.

$($b$)$ Now consider, Job A has $60$ second run time and arrives at time $0$ second. Process B and C has $10$ second runtime,

and arrive at time $10$ second. For STCF $($shortest time to completion$),$ what is average turnaround time? $(5$ points$)$

Average Turnaround time $($in seconds$)$: $36\mathrm{.}6$ sec

Part $2$: Scheduling Again! $(10$ points$)$

The multi$-$level feedback queue policy periodically moves all jobs back to the top$-$most queue $($let$$s call this MLFQ reset$).$

Let$$s assume that in our system this happes once every $10$ seconds. Once could shorten the MLFQ reset to $1$ second. List

one positive and negative effffect of reducing MLFQ reset frequency $(5$ points$)$

$+$ Pros

Reduces response time and wait time for processes in the lower levels and schedules them more frequently.

$-$ Cons

Incurs significant context switch cost and also requires frequently moving jobs across the queues.

You were given full points if you stated the correct behavior and the impact.