Simulates how an operating system manages processes and process queues.
Author: Anna Karingal
Date Created: February 27, 2015
Last Modified: May 10, 2015
Python Version: 2.7.6
The program is run from the command line using python main.py in the working directory.
Once you run the program, it will enter system generation (Sys Gen) mode and prompt you for information about the system, including how many devices are in the system, how many cylinders there are for each disk drive and some parameters for CPU scheduling like the history parameter (alpha) and intial burst estimate (Tau(0)).
CPU Scheduling is implemented using a history-based shortest job first approximation algorithm using the formula
Tau(next) = (alpha * Tau(previous)) + ((1-alpha) + t(previous))
where t(previous) is the actual previous CPU burst and Tau is the estimated burst. All processes are initialized with an estimated next burst of Tau(0).
Disk Scheduling is implemented using an FLOOK algorithm.
*Memory Management uses paging.
Once the program exits sys gen mode, the user can input commands to simulate system calls and new processes coming into the system. The user will also be prompted to enter how much time has elapsed between system calls, so that CPU scheduling can properly be implemented.
a -- Activates a new process
t -- Terminates current process in CPU
s -- Enters snapshot mode. Enter the prefix of the device type to see a list of processes in devices of that type. (p for printer, d for disk drive, c for CD drive or r for ready queue/CPU)
p1 -- enter the name of any device in lowercase to simulate the active process in the CPU requesting that device via a system call
P1 -- enter the name of any device in uppercase to simulate the active process in that device is finished and wants to go back into the ready queue.
k# -- Kill process with pid #
h -- Help to see a list of commands
q or Ctrl+D to quit
- Refactor!!