Memory Allocator with sbrk

Overview

This project demonstrates a custom implementation of a dynamic memory allocator using the sbrk system call. It manages memory allocation and deallocation with a best-fit strategy, a linked-list-based free list, and block splitting/coalescing mechanisms.

Key Features

1. Uses sbrk to request memory from the operating system.
2. Implements a best-fit strategy to find the most suitable free block for allocation.
3. Splits larger blocks into smaller usable and free blocks to optimize space usage.
4. Coalesces adjacent free blocks during deallocation to avoid fragmentation.

---

Memory Layout of a Linux Process

• Text: Stores the program's executable instructions.
• Data: Contains global and static variables.
• Heap: Dynamic memory managed by malloc, calloc, and free. It grows upward as more memory is allocated.
• Unallocated Memory: Space between the program break (managed with sbrk) and the stack.
• Stack: Stores local variables and function call information. It grows downward.

---

Free List Management

The free list tracks unused memory blocks that are available for future allocations. Each block contains metadata and pointers for a doubly linked list.

• Fields:
  • size: Size of the memory block.
  • prv: Pointer to the previous block.
  • nxt: Pointer to the next block.

Operations:

• Add newly freed blocks back to the free list.
• Merge adjacent free blocks during coalescing.

Memory Allocation Flowchart

This flowchart outlines the steps to allocate memory:

1. Check the free list for a suitable block:
   • If a block of the required size is found:
     • If it's larger than the requested size, split it into two blocks.
     • Use the required part and leave the remaining part in the free list.
   • If no suitable block is found, request more memory using sbrk(size).
2. Return the allocated memory to the caller.