Platform LSF Administration Guide Version 6.2

Time-based Slot Reservation
Administering Platform LSF
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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)
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.
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.
Some scheduling examples
1 Job5 requests –n 6 –R “span[ptile=2]”, which will require three hosts with 2 CPUs
on each host.
As in the greedy slot reservation example, Four jobs are running in the cluster:
Job1, Job2, Job3 and Job4. 2 CPUs are available now, 1 on host A, and 1 on
host
D:
2 Job2 finishes, freeing 2 more CPUs for future allocation, 1 on host A, and 1 on
host
C:
Job4 Job3 Job4 Job3
Job4 Job3 Job4 Job3
Job2 Job3 Job2
Job3 Job1 Job1
J
Current Inuse
Current available
A BCD
Job4 Job3 Job4 Job3
Job4 Job3 Job4 Job3
Job3
Job3 Job1 Job1
J
Current available
A BCD
Current Inuse
Future available