NexusAlloc

A high-performance, lock-free C++20 memory allocator designed for latency-sensitive applications.

Features

• 🔒 Lock-Free Design - Uses atomic operations (CAS) instead of mutexes
• 🧵 Thread-Local Arenas - Zero-contention fast-path allocations via thread_local
• 📄 Hugepage Support - Reduces TLB misses and page fault jitter with 2MB pages
• ⚡ O(1) Allocation - Slab-based segregated free lists for constant-time operations
• 🎯 SIMD-Friendly - 16-byte minimum alignment for all allocations
• 📊 STL Compatible - Drop-in replacement for std::allocator

Quick Start

#include <nexusalloc/nexusalloc.hpp>
#include <vector>

int main() {
    // Optional: Lock memory to prevent page faults
    nexusalloc::initialize();

    // Use with STL containers
    std::vector<int, nexusalloc::NexusAllocator<int>> vec;
    vec.push_back(42);

    // Or use directly
    void* ptr = nexusalloc::allocate(64);
    nexusalloc::deallocate(ptr, 64);
}

Building

# Debug build (default)
make build

# Release build
make build BUILD_TYPE=Release

# Run tests
make test

# Run benchmarks
make bench

Architecture

graph TB
    subgraph Application
        APP[Your Code]
    end

    subgraph "NexusAllocator<T>"
        ALLOC[STL Interface]
    end

    subgraph "Thread-Local Arena"
        TLA[Per-Thread, Zero Contention]
        S1["Slab<16>"]
        S2["Slab<32>"]
        S3["Slab<64>"]
        SN["..."]
    end

    subgraph "Global Page Stack"
        GPS[Lock-Free CAS]
    end

    subgraph "OS Layer"
        HP["HugepageProvider<br/>(mmap + MAP_HUGETLB)"]
    end

    APP --> ALLOC
    ALLOC --> TLA
    TLA --> S1
    TLA --> S2
    TLA --> S3
    TLA --> SN
    S1 -.->|chunk request| GPS
    S2 -.->|chunk request| GPS
    S3 -.->|chunk request| GPS
    SN -.->|chunk request| GPS
    GPS -.->|page alloc| HP

Loading

Size Classes

Range	Increment	Classes
1-256 bytes	16 bytes	16, 32, 48, ..., 256
257-65536 bytes	Power of 2	512, 1024, ..., 65536
>65536 bytes	Direct mmap	N/A

Enabling Hugepages

# Check current hugepage allocation
cat /proc/meminfo | grep Huge

# Reserve hugepages (requires root)
echo 100 | sudo tee /proc/sys/vm/nr_hugepages