QUICK RESPONSE PLEASE

I NEED HELP UNDERSTANDING HOW TO EXTEND THE XV6 and what this part is asking me to do.

This project is on xv6 scheduler. You are going to extend the xv6 system you built in P1. There

are three objectives to this assignment:

To familiarize yourself with a real scheduler like xv6 scheduler.

To change that scheduler to a new algorithm.

To display the scheduling information.

1 Revised MLFQ Design

The existing scheduler in xv6 is a Round-Robin (RR) scheduler. Upon each timer interrupt (every 10

ms), the interrupt handler switches to the kernel scheduler, which then selects the next runnable process

to run. This scheduler, while simple, is too primitive to do anything interesting. In this project, you

will be putting a new scheduler the revised Multi-Level Feedback Queue (rMLFQ) into xv6. It has

three queues: Qi, i = 1, 2, 3 with time quantum size 20 ms for Q1, 40 ms for Q2, and 80 ms for Q3. The

detailed policy is described as follows:

Any new process will be inserted to the end of Queue Q1;

The scheduler will always choose the front process in the highest-priority non-empty queue in the

order of Q1, Q2, and Q3;

Any chosen process will be scheduled for the queue-corresponding quantum size or the remaining

burst size if its remaining burst size is large enough;

If the process has nothing remaining, the process will be removed from the queue after its execution;

If the process is not done within this round, it shall be moved to the next lower-priority queue

except for any process in Q3;

Q3 runs a Round-Robin with time quantum size as 80 ms. If a process is not done within the

assigned quantum size, it remains in Q3 competing for more rounds. The scheduler adopts a

revised priority boosting in Q3. After tworounds, any unfinished job will be pushed to Q1. This

is different from the priority boosting discussed in class.