Question

1. What is the other name for Shortest Job First Preemptive Algorithm?

2. What are the 5 different states a process can be in scheduling (Look into process state

   diagram)?

3. Shortest Job First is like Priority Scheduling with the priority based on ______ of the

   process?

4. ________ effect is the primary disadvantage of First Come First Serve Scheduling

   algorithm.

5. How does Multi Level Feedback queue prevent starvation of processes that waits too

   long in lower priority queue?

Answer 1

1. Other name of Shortest Job First Preemptive Algorithm is Shortest Remaining Time First (SRTF).

2. Five different states in which process can be in scheduling :

• Created :- When a process is created.
• Ready :- When process is ready to run and it is loaded in main memory.
• Running :- Process is running and its instructions are being executed.
• Blocked :- Process is blocked due I/O wait or lack or memory.
• Terminated :- Either process is complete or killed using its PID.

3. Shortest Job First is like Priority Scheduling with the priority based on CPU Burst Time of the process.

4. Convoy effect is the primary disadvantage of First Come First Serve Scheduling algorithm.

5. To avoid starvation of process in Multi Level Feedback queue(MLFQ),we update the priorities of processes dynamically so that they don't have to wait for long time due to large processes .

     The following rule is used to update the priority of processes :

• When a process enters the system, it is placed in the highest priority queue.
• If priority of P1 process is equal to P2 process then both are run using round robin algorithm and have same time slice.
• If a process is using entire time-slice while running,its priority is reduced.
• If a process gives up the CPU before the time slice expires, it remains at the same priority level.

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Please comment in case you have any doubt.