Mini Project 2 CPU Sched Solved

# Scheduling Algorithms
  


This project involves implementing 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 round-robin 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. In addition, tasks do not have to be placed into a queue or list in any particular order.

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.

## 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.

## Deliverables

1. 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   
   ``` 
2. And calculating the *average* **turnaround time**, **waiting time**, and **response time** for each of the above
scheduling algorithms.