mbiel / mymalloc Goto Github PK

Mike Bielagus
CSCI E-251 PS2

Purpose -- The purpose of this project is to implement a malloc/free-like system for managing memory. The system should
work as described in the assignment specification.

Algorithm -- I decided to use the first-fit algorithm for this project, mainly on the basis of the information in
Tanenbaum, pp. 186-7. Tanenbaum suggests that first fit does slightly better than both next and best fit, and is
fairly simple to implement, so it seemed like the best choice. One choice I made for simplicity's sake that I
would probably change if I wanted a performance boost would be that instead of maintaining only a single list
for all blocks, whether allocated or free, I would maintain a second list containing only free blocks, so as 
not to waste time scanning blocks that were known to be allocated when looking for free space. You can see, if you recompile
with the debug flag off and run the commented-out code at the bottom of mymalloctest, that allocating a larger number of integers
takes a long time, while freeing them takes very little. I believe that maintaining a free list would improve the allocation speed.
However, in order to print the memory map, it was easier just to use a single list. By investigating the behavior of myMalloc and
myFree with the memoryMap function, it appears that blocks are being allocated in an appropriate way, and that
free space is being merged as it should. Since I did not implement best fit or another system, I was unfortunately 
not able to make comparisons between my algorithm and alternative methods. However, there were no obvious speed 
issues.

Interface -- The interface is described in the comments in the header file. mymalloctest is a test file that is intended
to test the behavior of myMalloc and myFree.