Slow And Asymmetric 10gb Virtio Speeds Between KVM Host And Guests

Feb 28, 2025 by ADMIN 67 views

Introduction

In the realm of virtualization, achieving high-speed networking between hosts and guests is crucial for efficient resource utilization and seamless communication. However, many users have reported experiencing slow and asymmetric speeds when using virtio networking in KVM environments. In this article, we will delve into the possible causes of this issue and explore potential solutions to optimize virtio speeds between KVM hosts and guests.

Understanding Virtio Networking

Virtio is a high-performance networking interface designed for virtualized environments. It allows for direct access to the host's network stack, eliminating the need for emulation and resulting in faster speeds. However, virtio networking also introduces complexities, such as the need for proper configuration and optimization.

KVM Host Configuration

To attempt testing KVM guest <=> host traffic speeds, I have set up the following KVM host:

/etc/netplan/01-enp8s0_LAN.yaml (physical Intel i226 2.5Gbe port)

network:
  version: 2
  ethernets:
    enp8s0:
      dhcp4: no
      dhcp6: no
      addresses: [192.168.1.100/24]
      gateway4: 192.168.1.1
      nameservers:
        addresses: [192.168.1.1, 8.8.8.8]
      mtu: 9000
      link-watch: true
      wakeonlan: true
      wakeonlan-arp: true
      wakeonlan-arp-timeout: 10
      wakeonlan-arp-count: 3
      wakeonlan-arp-interval: 1
      wakeonlan-arp-retries: 3
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-arp-retry-count: 3
      wakeonlan-arp-retry-timeout: 10
      wakeonlan-arp-retry-interval: 1
      wakeonlan-<br/>
**Slow and Asymmetric 10gb virtio Speeds Between KVM Host and Guests**
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**Q&A: Troubleshooting Slow and Asymmetric 10gb virtio Speeds**
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### Q: What are the common causes of slow and asymmetric virtio speeds between KVM hosts and guests?

A: There are several possible causes of slow and asymmetric virtio speeds between KVM hosts and guests, including:

* **Incorrect virtio configuration**: Virtio configuration can be complex, and incorrect settings can lead to slow speeds.
* **Network interface card (NIC) issues**: Issues with the host's NIC can cause slow speeds.
* **Virtio driver issues**: Issues with the virtio driver on the guest can cause slow speeds.
* **Guest operating system issues**: Issues with the guest operating system can cause slow speeds.
* **Host operating system issues**: Issues with the host operating system can cause slow speeds.

### Q: How can I troubleshoot slow and asymmetric virtio speeds?

A: To troubleshoot slow and asymmetric virtio speeds, follow these steps:

1. **Check virtio configuration**: Verify that the virtio configuration is correct and matches the host's NIC configuration.
2. **Check NIC issues**: Verify that the host's NIC is functioning correctly and is not causing any issues.
3. **Check virtio driver issues**: Verify that the virtio driver on the guest is functioning correctly and is not causing any issues.
4. **Check guest operating system issues**: Verify that the guest operating system is functioning correctly and is not causing any issues.
5. **Check host operating system issues**: Verify that the host operating system is functioning correctly and is not causing any issues.

### Q: What are some common virtio configuration issues that can cause slow speeds?

A: Some common virtio configuration issues that can cause slow speeds include:

* **Incorrect MTU setting**: The MTU (Maximum Transmission Unit) setting on the virtio interface can be set too low, causing packets to be fragmented and leading to slow speeds.
* **Incorrect queue settings**: The queue settings on the virtio interface can be set incorrectly, causing packets to be dropped and leading to slow speeds.
* **Incorrect interrupt settings**: The interrupt settings on the virtio interface can be set incorrectly, causing packets to be dropped and leading to slow speeds.

### Q: How can I optimize virtio speeds?

A: To optimize virtio speeds, follow these steps:

1. **Verify virtio configuration**: Verify that the virtio configuration is correct and matches the host's NIC configuration.
2. **Check NIC issues**: Verify that the host's NIC is functioning correctly and is not causing any issues.
3. **Check virtio driver issues**: Verify that the virtio driver on the guest is functioning correctly and is not causing any issues.
4. **Check guest operating system issues**: Verify that the guest operating system is functioning correctly and is not causing any issues.
5. **Check host operating system issues**: Verify that the host operating system is functioning correctly and is not causing any issues.

### Q: What are some best practices for optimizing virtio speeds?

A: Some best practices for optimizing virtio speeds include:

* **Use a high-performance NIC**: Use a high-performance NIC on the host to ensure that packets are transmitted quickly and efficiently.
* **Use a high-performance virtio driver**: Use a high-performance virtio driver on the guest to ensure that packets are transmitted quickly and efficiently.
* **Verify virtio configuration**: Verify that the virtio configuration is correct and matches the host's NIC configuration.
* **Check for NIC issues**: Verify that the host's NIC is functioning correctly and is not causing any issues.
* **Check for virtio driver issues**: Verify that the virtio driver on the guest is functioning correctly and is not causing any issues.

### Q: What are some common guest operating system issues that can cause slow speeds?

A: Some common guest operating system issues that can cause slow speeds include:

* **Incorrect network stack configuration**: The network stack configuration on the guest operating system can be set incorrectly, causing packets to be dropped and leading to slow speeds.
* **Incorrect virtio driver configuration**: The virtio driver configuration on the guest operating system can be set incorrectly, causing packets to be dropped and leading to slow speeds.
* **Incorrect interrupt settings**: The interrupt settings on the guest operating system can be set incorrectly, causing packets to be dropped and leading to slow speeds.

### Q: How can I troubleshoot guest operating system issues?

A: To troubleshoot guest operating system issues, follow these steps:

1. **Verify network stack configuration**: Verify that the network stack configuration on the guest operating system is correct and matches the host's NIC configuration.
2. **Verify virtio driver configuration**: Verify that the virtio driver configuration on the guest operating system is correct and matches the host's NIC configuration.
3. **Verify interrupt settings**: Verify that the interrupt settings on the guest operating system are correct and match the host's NIC configuration.

### Q: What are some common host operating system issues that can cause slow speeds?

A: Some common host operating system issues that can cause slow speeds include:

* **Incorrect network stack configuration**: The network stack configuration on the host operating system can be set incorrectly, causing packets to be dropped and leading to slow speeds.
* **Incorrect virtio driver configuration**: The virtio driver configuration on the host operating system can be set incorrectly, causing packets to be dropped and leading to slow speeds.
* **Incorrect interrupt settings**: The interrupt settings on the host operating system can be set incorrectly, causing packets to be dropped and leading to slow speeds.

### Q: How can I troubleshoot host operating system issues?

A: To troubleshoot host operating system issues, follow these steps:

1. **Verify network stack configuration**: Verify that the network stack configuration on the host operating system is correct and matches the host's NIC configuration.
2. **Verify virtio driver configuration**: Verify that the virtio driver configuration on the host operating system is correct and matches the host's NIC configuration.
3. **Verify interrupt settings**: Verify that the interrupt settings on the host operating system are correct and match the host's NIC configuration.