linux

Objectives

• Explain the importance of I/O scheduling
• Understand how Completely Fair Queue and Deadline algorithms work

I/O Scheduling

It is the interface between the generic block layer and the low-level physical device. Both Virtual Memory and Virtual File system layers submit I/O request to block devices, its the job of the I/O scheduling layer to prioritize and order these requests before they are given to the block devices.

Any I/O scheduling system has to satisfy certain conflicting requirements:

Introduction

The relationship among I/O and system performance is complex, in order to tackle the challenge of resource monitoring we can use iostat, iotop and ionice.

Objectives

• Use iostat to monitor system I/O device activity
• Use iotop to display a constantly updated table of current I/O usage
• Use ionice to set both the I/O scheduling class and the priority for a given process

iostat

Is the workhorse for I/O device activity monitoring on the system.