CPU Frequency Scaling

This topic details the various CPU frequency scaling methods supported by Vertica. In general, if you do not require CPU frequency scaling, then disable it so as not to impact system performance.

Important: Your systems may use significantly more energy when frequency scaling is disabled.

The installer allows CPU frequency scaling to be enabled when the cpufreq scaling governor is set to performance. If the cpu scaling governor is set to ondemand, and ignore_nice_load is 1 (true), then the installer fails with the error S0140. If the cpu scaling governor is set to ondemand and ignore_nice_load is 0 (false), then the installer warns with the identifier S0141.

CPU frequency scaling is a hardware and software feature that helps computers conserve energy by slowing the processor when the system load is low, and speeding it up again when the system load increases. This feature can impact system performance, since raising the CPU frequency in response to higher system load does not occur instantly. Always disable this feature on the Vertica database hosts to prevent it from interfering with performance.

You disable CPU scaling in your host's system BIOS. There may be multiple settings in your host's BIOS that you need to adjust in order to completely disable CPU frequency scaling. Consult your host hardware's documentation for details on entering the system BIOS and disabling CPU frequency scaling.

If you cannot disable CPU scaling through the system BIOS, you can limit the impact of CPU scaling by disabling the scaling through the Linux kernel or setting the CPU frequency governor to always run the CPU at full speed.

Caution: This method is not reliable, as some hardware platforms may ignore the kernel settings. The only reliable method is to disable CPU scaling in BIOS.

The method you use to disable frequency depends on the CPU scaling method being used in the Linux kernel. See your Linux distribution's documentation for instructions on disabling scaling in the kernel or changing the CPU governor.