An energy policy tag is created by submitting
jobs. The job runs using the default CPU frequency. When the job is
finished, LSF collects the following information and adds it to the
energy policy tag:
- Energy usage
- Job run time
- GIPS (giga instructions per second) for each computing
node.
- GBS (giga bytes per second) for each computing node.
Important: Jobs generating an
energy policy tag require exclusive use of the host. Therefore, the
command bsub –x must be used.
The energy policy tag name is specified using the esub
command when a job is submitted for the first time. For example:
bsub –x -a “eas(tag1,create)”
sleep 10
Based on the data collected from a job and the coefficient
data (which is collected using Benchmarking applications) LSF generates
an energy policy tag using a prediction method. Using this energy
policy tag, you can create an energy policy, specifying what CPU frequency
LSF should use for each job.
Two steps are involved in creating a job energy policy
tag:
- Generate energy policy tag - Run the job in the default
CPU frequency. When the job is done, LSF provides the energy consumption
for the default frequency and estimates the performance degradation
for each supported frequency. An energy policy tag name is generated
for the job. You may run the job more than once, using different default
CPU frequencies to see a variety of results.
- Automatically select CPU frequency – The same job is
submitted again with the same energy policy tag name. LSF will choose
the best suitable frequency for the job based on the energy policy
tag, user specified energy policy and settings in the global performance
threshold file.
To support energy policy tag generation and to enable
the automatic select CPU frequency feature, the following parameters
(in lsf.conf) must be defined:
- LSF_MANAGE_FREQUENCY=HOST
- LSF_COLLECT_ENERGY_USAGE=Y
- LSF_DEFAULT_FREQUENCY
For the automatic select CPU frequency feature, you
must also define the lsb.threshold configuration file, using the energy
tags.