A scheduling Algorithm assigns priority proportional to the waiting time of a…
2016
A scheduling Algorithm assigns priority proportional to the waiting time of a process. Every process starts with priority zero (lowest priority). The scheduler reevaluates the process priority for every ‘T’ time units and decides next process to be scheduled. If the process have no I/O operations and all arrive at time zero, then the scheduler implements _________ criteria.
- A.
Priority scheduling
- B.
Round Robin Scheduling
- C.
Shortest Job First
- D.
FCFS
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Correct answer: B
Answer: Round Robin Scheduling
Explanation: The scheduler assigns priority proportional to waiting time and reevaluates every T time units. With all processes arriving at time zero and no I/O, this dynamic priority rule causes the scheduler to give each ready process a turn in succession, effectively creating time slices of length T.
All processes start with equal priority (zero) at time zero.
The scheduler selects a process to run; after it runs, the others accumulate waiting time, increasing their priority relative to the one that just ran.
At each reevaluation (every T units) the process that has waited the longest is chosen next, so the scheduler cycles through processes in turn.
This behavior is equivalent to Round Robin with time quantum T (preemption at multiples of T and rotation among ready processes).
Note: Tie-breaking at the initial selection can be arbitrary, but once a process runs others will gain higher waiting-time-based priority, producing the cyclic Round Robin order.
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