Selecting the Algorithm for BrickOS Memory Management Allocation

Selecting the Algorithm for
BrickOS Memory Management
Allocation

An Extended Abstract for
Computer Projects
–

CMPS 490

What is BrickOS?


Open source OS
used in Dr. Bi’s Real
-
Time Systems
course.


Used to program
Lego Mindstorm
Robotics Command
eXplorer (RCX) 2.0
Robots.

Specifications of the RCX Computer


Hitachi H8/3292 single
-
chip
microcomputer.


System clock speed of 16MHz.


32kb of memory.


16 bit address space.


Various registers.

What is Memory Management?


A very vital part of any operating system.


Allocates and sets quota for memory
usage.


Also in control of protection of files.


There are four different methods
(algorithms) that can be used.

Different Algorithms for Memory
Management


First Fit
–

choose the first free block of ample
size in memory beginning at the start of user
memory.


Next Fit
–

choose the first free block of ample
size in memory beginning at the location of the
last block used.


Worst Fit
–

choose the free block that has the
biggest size in memory.


Best Fit
–

choose the free block that is the
smallest size in memory but is big enough.

The Problem.


The RCX unit has little memory and thus it
is a very scare resource.


Anything too advanced would result in too
much overhead.


BrickOS uses the most clear
-
cut method
for allocating memory, the first fit
algorithm.


This may not be the best algorithm to use.

The Solution


Modify BrickOS to allow a programmer the
ability to change the algorithm used for
memory management for each program
they code.


May become a useful tool helping students
who are first learning about memory
management of any operating system
including BrickOS.

Project Overview.


A very deep understanding of the BrickOS
Operating System and the C programming
language is needed to take on a project of
this magnitude.


Variables (both global and local) will have
to be created.


Functions will have to be modified and at
least 4 will have to be created.

Testing My Project.


Testing can be difficult.


Dr. Bi’s program example.


A joint effort with Charles (using his project
as a basis) we will create a memory
monitor.