LSF Version 7.3 - Administering Platform LSF

Time-based Slot Reservation
412 Administering Platform LSF
Greedy reservation example
A cluster has four hosts: A, B, C and D, with 4 CPUs each. Four jobs are running in
the cluster:
Job1, Job2, Job3 and Job4. According to calculated job estimated start
time, the job finish times (FT) have this order: FT(
Job2) < FT(Job4) < FT(Job1) <
FT(
Job3).
The highest priority pending job requests –n 6 –R “span[ptile=2]”. Based on this,
the job needs three hosts and two CPUs on each host. The default greedy slot
reservation calculates job start time as the job finish time of
Job4; after Job4
finishes, requested slots of pending job can be satisfied.
Configuring time-based slot reservation
Greedy slot reservation is the default slot reservation mechanism and time-based
slot reservation is disabled.
LSB_TIME_RESERVE_NUMJOBS (lsf.conf)
1 Use LSB_TIME_RESERVE_NUMJOBS=maximum_reservation_jobs in
lsf.conf to enable time-based slot reservation. The value must be a positive
integer.
LSB_TIME_RESERVE_NUMJOBS controls maximum number of jobs using
time-based slot reservation. For example, if
LSB_TIME_RESERVE_NUMJOBS=4, only the top 4 jobs will get their future
allocation information.
2 Use LSB_TIME_RESERVE_NUMJOBS=1 to allow only the highest priority
job to get accurate start time prediction.
Smaller values are better than larger values because after the first pending job
starts, the estimated start time of remaining jobs may be changed. For example,
you could configure LSB_TIME_RESERVE_NUMJOBS based on the number
of exclusive host partitions or host groups.
Absolute predicted start
time for all jobs
No No
Advance reservation
considered
No No
Start time prediction Time-based reservation Greedy reservation