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 low I/O latency

In this recipe, we are going to cover some of the disk performance optimization techniques by selecting an I/O scheduler and tuning the block I/O using Linux control groups, for the virtual guest and the host.

There are three I/O schedulers to choose from on the host OS and in the KVM instance:

  • noop: This is one of the simplest kernel schedulers; it works by inserting all incoming I/O requests into a simple FIFO (First In, First Out) queue. This scheduler is useful when the host OS should not attempt to reorder I/O requests when multiple virtual machines are running.
  • deadline: This scheduler imposes a deadline on all I/O operations to prevent starvation of requests, giving priority to read requests, due to processes usually blocking on read operations.
  • cfq: The main goal of Completely Fair Queuing (CFQ) is to maximize the overall CPU utilization while allowing better interactive performance.

Selecting the right I/O scheduler on the host and guests greatly...