Setting a default CPU frequency

Compute nodes run in the nominal frequency by default. When the node is idle or when it finishes running a job with an energy policy, the compute node switches back to the nominal frequency.

The parameter LSF_DEFAULT_FREQUENCY in lsf.conf allows you to set a default CPU frequency. Running a node at a lower CPU frequency by default will save energy.

The value of this parameter is in SI units (for example, GHz, MHz, KHz) and if no units are specified, it is considered GHz.

Note: LSF_DEFAULT_FREQUENCY will not be applied to master node or master candidate nodes.

If you are using the automatic CPU frequency selection feature and gathering benchmark data for use in generating an energy policy, the job should run under the default frequency. Any time the LSF_DEFAULT_FREQUENCY is modified, the coefficient data and energy policy tag must recalculate. Perform the following procedure if you change LSF_DEFAULT_FREQUENCY:

Stop the LSF cluster.
Run the initialize_eas script to generate new coefficient data for the new default CPU frequency.
This script may be run several times with different default CPU frequencies to generate several groups of coefficient data.
Start the LSF cluster.
To make a new default CPU frequency take effect, restart all sbatchd. If there are no running jobs, sbatchd sets the host to the default CPU frequency when it starts.
Generate the energy policy tag under the new default CPU frequency.

You may also use the script initialize_eas (in $LSF_BINDIR) which contains a parameter for a default CPU frequency to set on a compute node or list of nodes. This script should run on all compute nodes when configuring LSF. For example:

initialize_eas –n <node_list_file> -f <default_frequency>

The current setting for LSF_DEFAULT_FREQUENCY can be shown using the badmin command. For example:

bash-3.2$ badmin showconf mbd

LSF_DEFAULT_FREQUENCY = 2.5GHz

bash-3.2$ badmin showconf sbd

LSF_DEFAULT_FREQUENCY = 2.5GHz