Administering Platform LSF - SAS

Chapter 14
Fairshare Scheduling
dynamic priority = number_shares / (run_time * RUN_TIME_FACTOR)
Without the historical run time, the dynamic priority increases suddenly as
soon as the job finishes running because the run time becomes zero, which
gives no chance for jobs pending for other users to start.
When historical run time is included in the priority calculation, the formula
becomes:
dynamic priority = number_shares / (historical_run_time + run_time) *
RUN_TIME_FACTOR)
Now the dynamic priority increases gradually as the historical run time decays
over time.
Committed run time weighting factor
Configuring
Committed run time is the run time requested at job submission with the -W
option of bsub, or in the queue configuration with the RUNLIMIT parameter.
By default, committed run time does not affect the dynamic priority.
While the job is running, the actual run time is subtracted from the committed
run time. The user’s dynamic priority decreases immediately to its lowest
expected value, and is maintained at that value until the job finishes. Job run
time is accumulated as usual, and historical run time, if any, is decayed.
When the job finishes, the committed run time is set to zero and the actual run
time is added to the historical run time for future use. The dynamic priority
increases gradually until it reaches its maximum value.
Providing a weighting factor in the run time portion of the dynamic priority
calculation prevents a “job dispatching burst” where one user monopolizes job
slots because of the latency in computing run time.
Set a value for the COMMITTED_RUN_TIME_FACTOR parameter in
lsb.params. You should also specify a RUN_TIME_FACTOR, to prevent the
user’s dynamic priority from increasing as the run time increases.
If you have also enabled the use of historical run time, the dynamic priority is
calculated according to the following formula:
dynamic priority = number_shares / (cpu_time * CPU_TIME_FACTOR +
(historical_run_time + run_time) * RUN_TIME_FACTOR +
(committed_run_time - run_time) * COMMITTED_RUN_TIME_FACTOR +
(1 + job_slots) * RUN_JOB_FACTOR)
◆ committed_run_time
The run time requested at job submission with the -W option of bsub, or
in the queue configuration with the RUNLIMIT parameter. This calculation
measures the committed run time in hours.
In the calculation of a user’s dynamic priority,
COMMITTED_RUN_TIME_FACTOR determines the relative importance of the
committed run time in the calculation. If the -W option of bsub is not specified
at job submission and a RUNLIMIT has not been set for the queue, the
committed run time is not considered.
Administering Platform LSF 231