Priority scheduling in Operating Systems - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Priority Scheduling in operating systems?

Priority Scheduling is a method where each process is assigned a priority. The CPU is allocated to the process with the highest priority first.

beginner

How does Priority Scheduling decide which process runs next?

It selects the process with the highest priority to run next. If two processes have the same priority, other criteria like arrival time may be used.

intermediate

What is the difference between preemptive and non-preemptive Priority Scheduling?

In preemptive Priority Scheduling, a running process can be stopped if a higher priority process arrives. In non-preemptive, the running process continues until it finishes or blocks.

intermediate

What problem can occur in Priority Scheduling and how is it solved?

The problem is starvation, where low priority processes may never get CPU time. It can be solved by aging, which gradually increases the priority of waiting processes.

beginner

Give a real-life example that explains Priority Scheduling.

Imagine a hospital emergency room where patients with more serious conditions (higher priority) are treated before those with minor injuries, regardless of arrival time.

In Priority Scheduling, which process is selected to run first?

A The process that arrived first

B The process with the shortest burst time

C The process with the highest priority

D The process with the lowest priority

Priority Scheduling always selects the process with the highest priority to run first.

What happens in preemptive Priority Scheduling when a higher priority process arrives?

A The current process is stopped and the higher priority process runs

B The system crashes

C The new process waits in the queue

D The current process continues until it finishes

In preemptive Priority Scheduling, the CPU switches to the higher priority process immediately.

What is starvation in Priority Scheduling?

A When low priority processes never get CPU time

B When high priority processes wait too long

C When all processes get equal CPU time

D When the CPU is idle

Starvation happens when low priority processes keep waiting because higher priority processes keep arriving.

Which technique helps prevent starvation in Priority Scheduling?

A First Come First Serve

B Round Robin

C Shortest Job First

D Aging

Aging gradually increases the priority of waiting processes to prevent starvation.

In non-preemptive Priority Scheduling, when does the CPU switch to another process?

A Immediately when a higher priority process arrives

B Only when the current process finishes or blocks

C After a fixed time slice

D Never

In non-preemptive scheduling, the current process runs until it finishes or waits for I/O.

Explain how Priority Scheduling works and the difference between preemptive and non-preemptive types.

Think about how the CPU chooses which process to run and when it can switch.

Describe the problem of starvation in Priority Scheduling and how aging helps solve it.

Consider what happens to processes with low priority if higher priority ones keep coming.