Home Learn Linux Linux Documentation Linux How Tos Tracking Down High IO Wait in Linux

Tracking Down High IO Wait in Linux

NetworkOperationsTracking down performance issues in large distributed systems is inherently complicated. Why is the application slow? Where is the bottleneck? In my experience, one of the more insidious culprits is known as high IO wait. A place where, in the words of Dr. Seuss, everyone is just waiting.

The first indication of a high IO wait issue is normally system load average. The load average is computed based on CPU utilization, and includes the number of processes using or waiting to use the CPU, and, importantly on Linux, process that are in uninterruptible sleep. The load average can be interpreted on a basic level as being a CPU core at full utilization has a system load average of one. So, for a quad-core machine, a system load average of 4 would mean that the machine had adequate resources to handle the work it needed to do, but just barely. On the same quad-core system, a load average of eight would mean that if the server had eight cores instead of four, it would have been able to handle the work, but it is now overloaded. Maybe.


Read more at Ostatic


Subscribe to Comments Feed
  • shahzad Said:

    i am glad about your website. you get owsum information about solutions online marketing so please visit this website

Who we are ?

The Linux Foundation is a non-profit consortium dedicated to the growth of Linux.

More About the foundation...

Frequent Questions

Linux Training / Board

/** BC-056 Ameex changes to add tracking code - 2016-01-22 **/ ?>