## SR-IOV Overview

SR-IOV is a PCIe hardware virtualization technology that allows virtual machines to directly access physical network cards, bypassing the Hypervisor and significantly improving network performance.

## Core Concepts

### Physical Function (PF)

The Physical Function is the complete functional entity of the network card, possessing all network card resources. PF is managed by Host OS/Hypervisor and can configure and control the network card.

### Virtual Function (VF)

The Virtual Function is a lightweight分身 of the network card, derived from PF. VF can be directly assigned to virtual machines, with each VF sharing PF physical resources.

## How It Works

SR-IOV achieves IO resource virtualization at the hardware level:

1. Virtual machines can communicate directly with network card hardware
2. Avoids Hypervisor data path overhead
3. Achieves near-native network card performance

## Configuration on EZMAX Network Cards

### Enable SR-IOV

```bash
# Check SR-IOV capability
ethtool -i eth0

# Enable SR-IOV
echo 8 > /sys/class/net/eth0/device/sriov_numvfs

# Confirm VF created
lspci | grep Ethernet
```

### Assign VF to Virtual Machine

```bash
# Use virsh to assign VF
virsh attach-device hostdev --persistent
```

## Performance Benefits

实测数据表明，SR-IOV相比纯软件虚拟化：

- Latency reduced by 60-80%
- Throughput increased 3-5x
- CPU overhead reduced by 70%