Host CPU MHz Parameters Configuration

Some hosts support setting a maximum frequency for their CPU cores (application cores and platform cores) and the support for this configuration can be verified by looking at the is_max_cpu_configurable capability with the system host-show <host> command, that can assume two values: configurable or not-configurable. You may need to configure a maximum scaled frequency to avoid variability due to power and thermal issues when configured for maximum performance. For these hosts, the following parameters control the maximum frequency of their CPU cores:

• cpu_max_freq_min_percentage defines a system-wide minimum percentage of the maximum frequency allowed to be configured for CPUs. By default this parameter is set to 80, meaning that you can reduce the frequency only to a maximum of 80% of the max_cpu_mhz_allowed. There is no need to apply the platform service parameters after changing it.

  Note

  Run the Linux command sudo cpupower info on the host, to determine if the host has support for this configuration.

  ~(keystone_admin)] $ system service-parameter-modify platform config cpu_max_freq_min_percentage=<value-between-60-100>
  

  Note

  This parameter can be set between 60% and 100%.

• Configure max_cpu_mhz_configured to specify a maximum frequency for a particular host’s CPU cores.

  ~(keystone_admin)] $ system host-update <worker> max_cpu_mhz_configured=<frequency-in-MHz>
  

• To restore a host’s CPU cores’ max_cpu_mhz_configured value to it’s default value, the max_cpu_mhz_allowed label can be passed to the host-update command.

  ~(keystone_admin)] $ system host-update <worker> max_cpu_mhz_configured=max_cpu_mhz_allowed
  

Note

The configuration of host CPU MHz parameters needs a host lock/unlock.

Configure Parameters using the GUI

The Host CPU MHz parameters configuration can also be made using the GUI.

In Host Inventory > Edit Host modal, there is a CPU Frequency Configuration dropbox field to configure the Max CPU Frequency of the host.

If CPU Frequency Configuration is set to Default, then the hosts’ max_cpu_mhz_allowed value is used as the Max CPU Frequency of the host.

If CPU Frequency Configuration is set to Custom, then a Max CPU Frequency (MHz) field appears, allowing you to explicitly configure the Max CPU Frequency of the host. Note that the configured value can NOT be less than the value allowed by the service parameter cpu_max_freq_min_percentage.