MyHeap
Deadline: September 28th, 2014
1 Instructions
Implement your own version of C's malloc, realloc and free
using only mmap and munmap.
| Function |
Description |
|---|
| my_malloc(x) |
Allocate x bytes of memory and returns a pointer to the
allocated memory. Return 0 if no memory could be allocated. The
return address must be sufficiently aligned for C's long and
void* data types. |
| my_free(p) |
Deallocate the allocation pointed to by p, or do nothing if p is 0. |
| my_realloc(p, n) |
Reallocate the memory pointed to by p to fit n bytes of
memory instead. Return a pointer to the reallocated memory, or 0 if the reallocation failed. |
- each function must be implemented in a .c file of its own, named
after the function it contains. The function prototypes must be
declared in a .h file, in accordance with the C coding standard.
The submitted archive may (but needs not) include a test program.
You must include a Makefile which properly places the functions
in libminic.a.
- you may assume a page size of 8192 bytes.
- the only standard/system header you may include are <stddef.h>
and <sys/mman.h>; the only external functions you may use are
mmap and munmap (you may use functions from a previous assignment, by including their source in your submission).
2 Grading
- 6 points if my_malloc/my_free/my_realloc work as described. Tip: correctness > performance.
- +1 point if the implementation makes a best effort to fit multiple
small objects in a page.
- +0.5 point if my_malloc attempts to reuse memory that was most
recently freed.
- +1 point if the implementation makes a best effort at releasing
pages to the operating system.
- +0.5 point if the implementation determines the page size
automatically (using a portable mixture of getpagesize and
sysconf; for this extra grade you may include <unistd.h>).
- +1 point if the implementation provides its own wrappers for system calls.
3 Copyright and licensing
Copyright © 2014, Raphael ‘kena’ Poss. Permission is granted to
distribute, reuse and modify this document and other documents for the
Systems Programming course by the same author according to the terms
of the Creative Commons Attribution-ShareAlike 4.0 International
License. To view a copy of this license, visit
http://creativecommons.org/licenses/by-sa/4.0/.