Memory Management Simulator (C++)

CLI-based Operating System memory management simulator that models how modern OSes handle physical memory allocation, virtual memory, and cache hierarchy, with real-time statistics and visualization.

This project focuses on systems-level design, algorithmic correctness, and performance trade-offs in memory management.

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Objectives

• Simulate dynamic memory allocation and deallocation
• Implement multiple allocation strategies
• Model multilevel CPU cache hierarchies
• Implement paging-based virtual memory
• Observe fragmentation, cache behavior, and page faults

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Key Features

Physical Memory Management

• Simulates a contiguous block of physical memory
• Dynamic allocation and deallocation
• Allocation strategies:
  • First Fit
  • Best Fit
  • Worst Fit
• Correct block splitting and coalescing
• Tracks:
  • Used / free memory
  • External fragmentation
  • Allocation success / failure
  • Memory utilization

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Buddy Memory Allocator

• Power-of-two memory management
• Allocation size rounded to nearest power of two
• Recursive block splitting
• Buddy coalescing on deallocation
• Tracks:
  • Internal fragmentation
  • Allocation statistics
  • Memory utilization

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Allocation Modes

• AUTO — Power-of-two requests routed to Buddy allocator
• PHYSICAL — Always use physical allocator
• BUDDY — Always use buddy allocator
• FORCED — Explicit override mode

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Virtual Memory Simulation

• Paging-based virtual memory
• Per-process page tables
• Virtual → Physical address translation
• Page replacement policies:
  • FIFO
  • LRU
  • CLOCK
• Tracks:
  • Page faults
  • Page replacements
  • Page fault rate
  • Free / total frames

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Cache Hierarchy Simulation

• Multi-level cache hierarchy:
  • L1 Cache
  • L2 Cache
  • L3 Cache
• Configurable cache size, line size, and associativity
• Replacement policies:
  • FIFO
  • LRU
• Memory access flow:

Virtual Address → Page Table → Physical Address → L1 → L2 → L3 → Main Memory

Statistics Tracked (Cache)

• Cache hits and misses per level
• Hit ratios
• Main memory accesses
• Average Memory Access Time (AMAT)

Command Line Interface (CLI)

The simulator provides an interactive command-line interface to control all components of the memory system.

Example Usage

memsim> init
memsim> create 1
memsim> setproc 1
memsim[P1 | AUTO | LRU]> alloc 4KB
memsim[P1 | AUTO | LRU]> access 0
memsim> stats

Supported Commands

System

• init — Initialize the memory system
• quit — Exit the simulator
• help — Display all available commands

Process Management

• create <pid> — Create a new process
• setproc <pid> — Set current process context
• terminate <pid> — Terminate a process
• process [pid] — Display process information

Memory Allocation

• alloc <size> — Allocate memory (supports B / KB / MB)
• free <pid> <address> — Free allocated memory
• mode <auto|buddy|physical|forced> — Set allocation mode
• strategy <first|best|worst> — Set physical allocation strategy

Virtual Memory

• access <address> [write] — Access virtual memory
• policy <fifo|lru|clock> — Set page replacement policy

Inspection & Testing

• dump — Dump physical memory layout
• stats — Show system statistics
• bench [alloc|cache] — Run benchmarks
• test [name] — Run predefined memory tests

UI / UX

• color <on|off> — Toggle colored output

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Build & Run Instructions

Prerequisites

• C++17 compatible compiler
• CMake
• Ninja (recommended)

Build Steps

mkdir build
cd build
cmake ..
ninja
./memory-simulator

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Project Structure

memory-simulator/
├── src/
│   ├── allocator/
│   ├── buddy/
│   ├── cache/
│   ├── virtual_memory/
│   ├── cli/
│   └── main.cpp
├── include/
├── tests/
├── docs/
├── CMakeLists.txt
└── README.md

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📸 Demonstration

🎥 Demo Video

Allocation & Fragmentation

Memory Layout (Dump)

Allocation Statistics

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Buddy Allocator

Buddy Memory Layout

Buddy Allocator Statistics

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Cache & Virtual Memory

Cache + Virtual Memory Access Flow

Cache & VM Statistics

Design Highlights

• Clean separation between allocators, cache, and virtual memory
• Modular and extensible architecture
• Accurate modeling of OS memory-management behavior
• Emphasis on correctness and performance trade-offs

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Limitations

• No real disk I/O (page faults are symbolic)
• Single-threaded simulation
• Timing values are relative, not hardware-accurate