Operating Systems - Project 2
Spring 2025 | Koç University
- Sinemis Toktaş
This repository showcases Project 2 from the Operating Systems course completed at Koç University during Spring 2025. The project implements a comprehensive memory management simulator supporting contiguous memory allocation using three fundamental algorithms with both interactive and scripted execution modes.
- First Fit (F): Allocates memory in the first available hole large enough
- Best Fit (B): Allocates memory in the smallest suitable hole
- Worst Fit (W): Allocates memory in the largest available hole
- Case-Insensitive: Supports both uppercase and lowercase strategy flags
- Request (RQ): Allocate contiguous memory blocks with specified strategy
- Release (RL): Deallocate memory with automatic adjacent hole merging
- Compact (C): Consolidate fragmented holes into single contiguous block
- Status (STAT): Display comprehensive memory layout and allocation map
- Exit (X): Graceful program termination
- Interactive Mode: Real-time command processing with user prompts
- Scripted Mode: Batch execution from command files with final status output
- Error Handling: Robust validation with detailed error messages
- Dynamic Memory Management: Doubly-linked list for efficient operations
- Automatic Hole Merging: Combines adjacent free blocks on deallocation
- Fragmentation Prevention: Smart compaction algorithm
- Memory Safety: Comprehensive bounds checking and validation
# Compile and run
gcc starter-code.c -o allocator
./allocator 1048576
# Example session
allocator> RQ P0 40000 W # Request 40KB using Worst Fit
allocator> RQ P1 25000 F # Request 25KB using First Fit
allocator> STAT # Display memory status
allocator> RL P0 # Release P0's memory
allocator> C # Compact memory holes
allocator> X # Exit# Execute batch commands
./allocator 1048576 commands.txt
# Example commands.txt:
# RQ P1 100000 B
# RQ P2 50000 F
# RL P1
# C- Block Structure: Doubly-linked list nodes with PID, base address, and size
- Memory Management: Dynamic hole tracking with efficient insertion/deletion
- Process Validation: Duplicate PID prevention and existence checking
// Memory allocation with strategy selection
void allocate(char* PID, int size, char *strategy)
// Deallocation with automatic merging
void deallocate(char* PID)
// Memory compaction with address recalculation
void compact()
// Comprehensive status reporting
void status()memory-allocator/
├── starter-code.c # Main implementation
├── allocator # Compiled executable
├── Makefile # Build configuration
└── README.md # This file
Addresses [0:315000] Process P1
Addresses [315001:512500] Process P3
Addresses [512501:625575] Unused
Addresses [625576:725100] Process P6
Addresses [725101:1048575] Unused
ERROR: Insufficient memory to allocate to the request.
ERROR: Given PID already exists!
ERROR: Given PID does not exist in memory.
- Efficient Allocation: O(n) time complexity for all allocation strategies
- Smart Merging: Automatic combination of adjacent holes during deallocation
- Compaction Strategy: Moves all processes to top, creates single hole at bottom
- Fragmentation Handling: Minimizes external fragmentation through compaction
- Input Validation: Comprehensive argument checking and error reporting
- Memory Safety: Proper allocation/deallocation with leak prevention
- Edge Case Handling: Boundary conditions and invalid operations
- Cross-Platform: Compatible across different Linux distributions
This project demonstrates proficiency in:
- Memory Management: Practical implementation of allocation algorithms
- Data Structures: Dynamic linked list operations and manipulation
- Algorithm Analysis: Understanding of different allocation strategy trade-offs
- System Design: Modular architecture with clean separation of concerns
- C Programming: Advanced pointer manipulation and memory operations