LSF Version 7.3 - Administering Platform LSF

Administering Platform LSF 299
Fairshare Scheduling
❖ For queue-level fairshare, LSF measures the resource consumption of all
the user’s jobs in the queue. This means a user’s dynamic priority can be
different in every queue.
❖ For host partition fairshare, LSF measures resource consumption for all the
user’s jobs that run on hosts in the host partition. This means a user’s
dynamic priority is the same in every queue that uses hosts in the same
partition.
◆ For queue-based fairshare, LSF measures the resource consumption of all jobs
in each queue.
Default dynamic priority formula
By default, LSF calculates dynamic priority according to the following formula:
dynamic priority = number_shares / (cpu_time * CPU_TIME_FACTOR + run_time
* RUN_TIME_FACTOR + (1 + job_slots) * RUN_JOB_FACTOR)
The maximum value of dynamic user priority is 100 times the number of user
shares (if the denominator in the calculation is less than 0.01, LSF rounds up to
0.01).
For cpu_time, run_time, and job_slots, LSF uses the total resource consumption of
all the jobs in the queue or host partition that belong to the user or group.
number_shares The number of shares assigned to the user.
cpu_time The cumulative CPU time used by the user (measured in hours). LSF calculates the
cumulative CPU time using the actual (not normalized) CPU time and a decay
factor such that 1 hour of recently-used CPU time decays to 0.1 hours after an
interval of time specified by HIST_HOURS in
lsb.params (5 hours by default).
run_time The total run time of running jobs (measured in hours).
job_slots The number of job slots reserved and in use.
Configuring the default dynamic priority
You can give additional weight to the various factors in the priority calculation by
setting the following parameters in
lsb.params.
◆ CPU_TIME_FACTOR
◆ RUN_TIME_FACTOR
◆ RUN_JOB_FACTOR
◆ HIST_HOURS
If you modify the parameters used in the dynamic priority formula, it affects every
fairshare policy in the cluster.
CPU_TIME_FACTOR The CPU time weighting factor.
Default: 0.7
RUN_TIME_FACTOR The run time weighting factor.
Default: 0.7