Dynamic Memory Allocator

This project implements a custom dynamic memory allocator in C, similar to the malloc() and free() functions in the standard C library.

Features

• Explicit free list implementation for efficient memory management
• First-fit allocation strategy
• Immediate coalescing of free blocks
• Boundary tag coalescing for O(1) time free operation
• Optimized for both space utilization and throughput

Implementation Details

The allocator uses the following key data structures and algorithms:

• block_info struct to represent heap blocks, containing size/tag info and free list pointers
• Explicit free list with LIFO insertion policy
• Boundary tags in both allocated and free blocks to enable efficient coalescing
• First-fit search for finding free blocks
• Splitting of large free blocks to reduce internal fragmentation
• Immediate coalescing of adjacent free blocks on free operations

Key functions:

• mm_init: Initialize the allocator
• mm_malloc: Allocate a block of memory
• mm_free: Free an allocated block
• coalesce_free_block: Merge adjacent free blocks
• request_more_space: Expand the heap when necessary

Usage

The allocator can be used as a drop-in replacement for malloc/free:

#include "mm.h"

int main() {
  mm_init();
  
  int *arr = (int*)mm_malloc(10 * sizeof(int));
  
  // Use allocated memory
  
  mm_free(arr);
  
  return 0;
}

Building and Testing

A Makefile is provided to build the allocator and run tests:

make         # Build allocator
make check   # Run tests

The test driver (mdriver) runs the allocator through a series of trace files to check correctness and measure performance.

Performance

The allocator aims to balance space utilization and throughput. On the provided trace files, it achieves:

• Space utilization: ~75%
• Throughput: ~80% of libc malloc

Future Improvements

Potential areas for optimization:

• Segregated free lists
• Better splitting heuristics
• Deferred coalescing