Performance tuning

This page describes how to improve performance of OpenVZ system.

HW node environment tuning

Disable unnecessary services

Disable all default services that you do not need to use and then reboot your host.

For example, the audit daemon can significantly decrease performance of linux kernel system calls (up to ~20%) even if you do not use any audit rules, or even if you just stopped this service without host reboot!

To setup default services, use chkconfig or ntsysv in RedHat, or rc-update in Gentoo, update-rc.dv on Debian

network checksumming

(TODO)

Virtual Environment tuning

CPU distribution inside VE on SMP hosts

• If the total number of VE's in your host is more than CPUs number, and there are many tasks running inside each VE, and they are scheduled quite often, it's better to give just one CPU for each VE. In this case the VirtualCPU-scheduler overhead can be significantly decreased, and overall performance can be increased up to ~50-100%!

To set the number of CPUs available inside VE use:

# vzctl set $VEID --cpus N

Recompiling the kernel

Disable all unnecessary options

• You can disable all _DEBUG_ options in the kernel, this can increase performance up to ~20% on some applications.

• other options (TODO)