EECS3221_Porject_CPU: A C repository from ajs0429

Scheduling Algorithms

Start: October 25, 2021, at 09:00am
Due: November 15, 2021, at 09:00pm

This project involves implementing (i.e., simulating) several different process scheduling algorithms. The scheduler will be assigned a predefined set of tasks and will schedule the tasks based on the selected scheduling algorithm. Each task is assigned a priority and CPU burst. The following scheduling algorithms will be implemented:

First-come, first-served (FCFS), which schedules tasks in the order in which they request the CPU.
Shortest-job-first (SJF), which schedules tasks in order of the length of the tasks’ next CPU burst.
Priority scheduling, which schedules tasks based on priority.
Round-robin (rr) scheduling, where each task is run for a time quantum (or for the remainder of its CPU burst).
Priority with round-robin, which schedules tasks in order of priority and uses round-robin scheduling for tasks with equal priority.

Priorities range from 1 to 10, where a higher numeric value indicates a higher relative priority. For rr scheduling, the length of a time quantum is 10 milliseconds.

Implementation

The implementation of this project may be completed in C and program files supporting the project are provided in the StartKit-Code folder. These supporting files read in the schedule of tasks, insert the tasks into a list, and invoke the scheduler. The schedule of tasks has the form [task name][priority][CPU burst], with the following example format:

T1, 4, 20   
T2, 2, 25   
T3, 3, 25   
T4, 3, 15   
T5, 10, 10

Thus, task T1 has priority 4 and a CPU burst of 20 milliseconds, and so forth. It is assumed that all tasks arrive at the same time, so your scheduler algorithms do not have to support higher-priority processes preempting processes with lower priorities. Tasks must be placed into a queue or list in the order they appear in the input.

There are a few different strategies for organizing the list of tasks, as first presented in Section 5.1.2. One approach is to place all tasks in a single unordered list, where the strategy for task selection depends on the scheduling algorithm. For example, SJF scheduling would search the list to find the task with the shortest next CPU burst. Alternatively, a list could be ordered according to scheduling criteria (that is, by priority). One other strategy involves having a separate queue for each unique priority, as shown in Figure 5.7. These approaches are briefly discussed in Section 5.3.6. It is also worth highlighting that we are using the terms list and queue somewhat interchangeably. However, a queue has very specific FIFO functionality, whereas a list does not have such strict insertion and deletion requirements. You are likely to find the functionality of a general list to be more suitable when completing this project.

Processes should be run in the order they appear in the input. Processes with equal priorities or burst times should be executed in the order they appear in the input. This applies to ties that may arise during SJF, Priority or Priority with round-robin scheduling (see example output below).

Implementation Details

The file driver.c reads in the schedule of tasks, inserts each task into a linked list, and invokes the process scheduler by calling the schedule() function. The schedule() function executes each task according to the specified scheduling algorithm. Tasks selected for execution on the CPU are determined by the pickNextTask() function and are executed by invoking the run() function defined in the CPU.c file. A Makefile is used to determine the specific scheduling algorithm that will be invoked by driver. For example, to build the FCFS scheduler, we would enter:

make fcfs

and would execute the scheduler (using the schedule of tasks schedule.txt) as follows:

./fcfs schedule.txt

Before proceeding, be sure to familiarize yourself with the source code provided as well as the Makefile.

Example output

The correct output of a sample input file for all algorithms can be seen here.

Deliverables

Completing this project will require writing the following C files, which invoke the appropriate scheduling algorithm:

schedule_fcfs.c   
schedule_sjf.c   
schedule_rr.c   
schedule_priority.c     
schedule_priority_rr.c

And calculating the average turnaround time, waiting time, and response time for each of the above scheduling algorithms.
You need to submit one zip file, project2.zip that includes the starter code (even if it was not modified), Makefile and any source files that were added. Do not submit object (*.o) files or compiled executables.

Note 1: here is a quick tutorial on makefile, in case you are not familiar.

Note 2: TAs will evaluate your projects on one of the Department's servers with specific configuration. You need to configure your account on one of the department servers according to this specific configuration. To do so, you may take a look at a how-to tutorial that is available in the course's eClass under the Project section.

Evaluation

Correct implementation of each algorithm will get 4 marks which make a total of 20 points for project 2. The 4 marks for each algorithm is broken down as follow: