WBJECA 2025 — Computer PYQ

CPU scheduling algorithms are classified by whether they allow the operating system to interrupt a currently running process (preemptive) or require the process to finish its CPU burst before the scheduler selects a new one (non-preemptive).

• SJF (Shortest Job First): Can be implemented as non-preemptive (standard SJF) or preemptive (SRTF).

• Priority Scheduling: Can be implemented as non-preemptive (a process finishes its burst) or preemptive (a new process with a higher priority arrives and preempts the current process).

• FCFS: Is inherently non-preemptive.

• Round Robin: Is inherently preemptive (based on time slices/quantums).

To represent this mathematically regarding scheduling modes:

$$\text{Mode}\in \{\text{Preemptive},\text{Non-preemptive}\}$$

$$\text{Algorithm Capability}=\{A\mid A\text{ supports }\text{Preemptive}\cap A\text{ supports }\text{Non-preemptive}\}$$

Therefore:

$$\{\text{SJF, Priority Scheduling}\}\subseteq \text{Algorithm Capability}$$