Book Image

KVM Virtualization Cookbook

By : Konstantin Ivanov
Book Image

KVM Virtualization Cookbook

By: Konstantin Ivanov

Overview of this book

Virtualization technologies such as KVM allow for better control over the available server resources, by deploying multiple virtual instances on the same physical host, or clusters of compute resources. With KVM it is possible to run various workloads in isolation with the hypervisor layer providing better tenant isolation and higher degree of security. This book will provide a deep dive into deploying KVM virtual machines using qemu and libvirt and will demonstrate practical examples on how to run, scale, monitor, migrate and backup such instances. You will also discover real production ready recipes on deploying KVM instances with OpenStack and how to programatically manage the life cycle of KVM virtual machines using Python. You will learn numerous tips and techniques which will help you deploy & plan the KVM infrastructure. Next, you will be introduced to the working of libvirt libraries and the iPython development environment. Finally, you will be able to tune your Linux kernel for high throughput and better performance. By the end of this book, you will gain all the knowledge needed to be an expert in working with the KVM virtualization infrastructure.
Table of Contents (15 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback

Tuning the kernel for network performance

Most modern Linux kernels ship sufficiently tuned for various network workloads. Some distributions provide predefined tuning services (a good example is tuned for Red Hat/CentOS), which include a set of profiles based on the server role.

Let's go over the steps taken during data transmission and reception, on a typical Linux host, before we delve into how to tune the hypervisor:

  1. The application first writes the data to a socket, which in turn is put in the transmit buffer.
  2. The kernel encapsulates the data into a Protocol Data Unit (PDU).
  3. The PDU is then moved onto the per-device transmit queue.
  4. The Network Interface Cards (NIC) driver then pops the PDU from the transmit queue and copies it to the NIC.
  5. The NIC sends the data and raises a hardware interrupt.
  6. On the other end of the communication channel, the NIC receives the frame, copies it on the receive buffer, and raises hard interrupt.
  7. The kernel in turn handles the interrupt and raises a soft interrupt...