Skip to content

README.md

Latest commit

 

History

History
136 lines (102 loc) · 4.4 KB

README.md

File metadata and controls

136 lines (102 loc) · 4.4 KB

Magma.AF_XDP

AF_XDP (Address Family XDP) integration for high-performance packet I/O on modern Linux kernels.

Overview

This module provides integration with Linux AF_XDP (XDP sockets) for zero-copy, high-performance packet processing. AF_XDP is the modern, kernel-native approach for high-speed networking on Linux, available since kernel 4.18.

Requirements

  • Linux kernel 4.18 or newer
  • XDP-capable network driver
  • libbpf library (for user-space XDP socket management)
  • Root privileges or CAP_NET_RAW capability

Advantages over NetMap

  • Mainline kernel support: No need to build and load out-of-tree kernel modules
  • Better security: Leverages eBPF/XDP framework with verifier
  • Active development: Part of the Linux kernel, actively maintained
  • Modern API: Clean socket-based interface
  • Zero-copy: Direct access to NIC memory when supported

Architecture

AF_XDP uses a socket-based API with ring buffers for efficient packet processing:

User Space:
┌─────────────────────────────────────┐
│  AF_XDPTransport                    │
│  ├─ AF_XDPPort                      │
│  │  ├─ XDP Socket                   │
│  │  ├─ UMEM (User Memory)           │
│  │  ├─ TX Ring (AF_XDPTransmitRing) │
│  │  └─ RX Ring                      │
│  └─ TcpTransportReceiver            │
└─────────────────────────────────────┘
         │
         ↓ (XDP socket)
Kernel Space:
┌─────────────────────────────────────┐
│  XDP Program (eBPF)                 │
│  └─ Packet filtering/steering       │
└─────────────────────────────────────┘
         │
         ↓
┌─────────────────────────────────────┐
│  Network Interface Card (NIC)       │
└─────────────────────────────────────┘

Implementation Status

This is a complete implementation of AF_XDP integration for Magma. The implementation includes:

  1. Native libbpf bindings: P/Invoke declarations for libbpf functions in Interop/LibBpf.cs

    • xsk_socket__create() - XDP socket creation
    • xsk_umem__create() - UMEM area management
    • xsk_ring_prod__*() and xsk_ring_cons__*() - Ring buffer operations

  2. UMEM management: AF_XDPMemoryManager handles user-space memory regions for packet buffers

  3. Ring buffer operations: Full TX/RX ring management with zero-copy semantics

  4. Packet receive loop: Efficient polling-based packet reception in dedicated thread

The implementation is production-ready for Linux systems with:

  • Linux kernel 4.18 or newer
  • libbpf.so.1 library installed
  • XDP-capable network driver

Usage Example

var options = new AF_XDPTransportOptions
{
    InterfaceName = "eth0",
    QueueId = 0,
    UseZeroCopy = true,
    UmemFrameCount = 4096,
    FrameSize = 2048
};

var transport = new AF_XDPTransport(
    new IPEndPoint(IPAddress.Parse("192.168.1.100"), 8080),
    options.InterfaceName,
    dispatcher
);

await transport.BindAsync();

Setup Instructions

1. Verify Kernel Support

# Check kernel version (need 4.18+)
uname -r

# Verify XDP support in your NIC driver
ethtool -i eth0 | grep driver

2. Install Dependencies

Ubuntu/Debian:

sudo apt-get install libbpf-dev linux-headers-$(uname -r)

Fedora/RHEL:

sudo dnf install libbpf-devel kernel-devel

3. Check NIC Capabilities

# Some NICs support native XDP, others only generic XDP
ip link show eth0

Performance Considerations

  • Native XDP mode: Best performance, requires driver support
  • Generic XDP mode: Fallback, works with any NIC but lower performance
  • Zero-copy: Only available with native XDP and supported drivers (e.g., i40e, ixgbe)
  • Queue binding: Bind to specific queues for multi-core scalability

References