Overview
You are going to be adding multi-threading capabilities to
Nachos. From the Unix point of view, Nachos is a process with user
space threads. From the Nachos point of view, Nachos is an operating
system that has processes without multi-threading. This assignment
requires that you add multi-threading in Nachos as follows:
1. Create a Process class
2. Integrate the Process class with the Nachos Threads and System
3. Change the scheduler
You need to make some extensions to the Nachos operating system.
Task 1 (20pts) : Create a new class called Process in files
(process.cc|h). Put the class in the threads directory and make sure
everything compiles. At a minimum the Process class will need only
constructor, destructor and some setter/getter functions.
• Determine what the member variables of the Process class should
be and which member variables, if and, need to be pulled out of
the Thread class (Nachos existing class)
o You need to explain why you decided the member variables in
Process class
o If you changed something in the Thread class, explain what
you changed in both the Thread class and Process class
Task 2 (30pts): Make your Nachos system run with processes. Create
Process functions and Thread Fork function.
• Process::Fork – Forks off a child process
• Process::Terminate – Terminates the running process
• Process::Join – Makes a parent process block until all of the
listed child processes have terminated. (BONUS – 10 pts)
• Thread::Fork – Forks off a new thread within this process. You
can assume that this thread is a thread in user space. Change the
existing Thread class.
You may need to change other files to run your NEW processes and
threads.
Task 3 (40pts): Processes now will be added a priority. The Process
constructor takes a priority as a parameter. Each process will take
the CPU according to its priority. In this assignment, priorities will
be between 1 and 5, 5 being the highest.
• Priority-based scheduling scheduler
o For example, when two processes have the same priority,
Process A has three user threads and Process B has one
thread. All three threads of Process A must share the CPU
time of Process A. The only one thread of Process B takes
the CPU time for Process B.
o What is your solution to schedule user threads in the same
process?
• Add a Nachos flag -quantum xxxx that sets how long the time
quantum will be for each process.
Task 4 (10pts): Write your own threadtest.cc to prove your multithreading
implementation working correctly. Quality of your testing
cases will be graded.
• You need to create meaningful number of Processes and Threads in
your testing routine.
• You need to display meaningful information to prove your multithreading:
Which process is running, which thread is running,
Process Fork, Terminate and Join, and Thread Fork calls are made.
Testing:
We will build and run your Nachos on the VM. The TAs will create their
own copy of threadtest.cc which will test your multi-threading. Make
sure that your solutions are general and robust so they will not
break.