Project ForgeA scheduling algorithm assigns priority proportional to the waiting time of a process. Every process starts with priority zero (the lowest priority). The scheduler re-evaluates the process priorities every T time units and decides the next process to schedule. Which one of the following is TRUE if the processes have no I/O operations and all arrive at time zero?
- AThis algorithm is equivalent to the first-come-first-serve algorithm.
- This algorithm is equivalent to the round-robin algorithm.
- CThis algorithm is equivalent to the shortest-job-first algorithm.
- DThis algorithm is equivalent to the shortest-remaining-time-first algorithm.
Explanation
Every T time units, whichever process just ran has its waiting time (and hence priority) reset to the lowest value, since it wasn't waiting while running — while every other process has been accumulating waiting time and now has strictly higher priority. Since all processes arrived simultaneously with no I/O to break the symmetry, this forces the scheduler to cycle through every process in turn, giving each a fixed T-length turn before moving to the next-longest-waiting one — which is exactly round-robin scheduling with time quantum T.
Source: GATE CS 2013 (2013)
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