CPU留学生编程辅导、C++程序语言调试、c++程序讲解

日期：2021-05-10 08:21

Operating Systems
Lab 04：CPU Scheduling Algorithms (FCFS and SJF)
Goals:
In this lab, you will simulate the following CPU scheduling algorithms:
? First Come First Served (FCFS): In FCFS scheduling, each process will be CPU scheduled
based on its arrival time in the ready queue.
? Non-preemptive Shortest Job First (SJF): The SJF scheduling algorithm scheduled
processes for running on CPU based on their CPU burst time; the process with the shortest
CPU burst time is scheduled first. If two processes with the same CPU burst time exists in the
ready queue, then FCFS scheduling approach is applied.
Given n processes with their burst times, the task is to find average waiting time and average
turnaround time using FCFS and SJF scheduling algorithms.
Policies:
It should go without saying that all the work that you will turn in for this lab will be yours. Do not
surf the web to get inspiration for this assignment, do not include code that was not written by you.
You should try your best to debug your code on your own, but it’s fine to get help from a colleague
as long as that means getting assistance to identify the problem and doesn’t go as far as receiving
source code to fix it (in writing or orally).
Contents:
Write a C program that simulates the FCFS and non-preemptive SJF CPU scheduling algorithms.
Repeat this experiment with different sets of processes and trace the waiting and turnaround times
for each process.
Here we are considering that arrival time for all processes is 0.
Completion Time: Time at which process completes its execution.
Turnaround Time: Time Difference between completion time and arrival time.
Turnaround Time = Completion Time – Arrival Time
Waiting Time: Time Difference between turnaround time and burst time.
Waiting Time = Turn Around Time – Burst Time
In this task, we have assumed arrival times as 0, so turn around and completion times are same.
1- Input the processes along with their burst time (bt).
2- Find waiting time (wt) for all processes.
3- As first process that comes need not to wait so
waiting time for process 1 will be 0 i.e. wt[0] = 0.
4- Find waiting time for all other processes i.e. for
process i ->
wt[i] = bt[i-1] + wt[i-1] .
5- Find turnaround time = waiting_time + burst_time
for all processes.
6- Find average waiting time =
total_waiting_time / no_of_processes.
7- Similarly, find average turnaround time =
total_turn_around_time / no_of_processes.
Expected Results:
FCFC:
SJF:
What should you submit:
1) Please submit a zip file which includes the C code of the two
algorithms:
2) Your zip file should be named as: “姓名_lab4”
3) Please submit your zip file by sending email to me as attachment:
my email address is: hzb564@jnu.edu.cn