LSF Version 7.3 - Administering Platform LSF

Reserving Memory for Pending Parallel Jobs
512 Administering Platform LSF
time starts from the time the first slot is reserved. When the reservation time
expires, the job cannot reserve any slots for one scheduling cycle, but then the
reservation process can begin again.
If you specify first execution host candidates at the job or queue level, LSF tries to
reserve a job slot on the first execution host. If LSF cannot reserve a first execution
host job slot, it does not reserve slots on any other hosts.
Configure processor reservation
1 To enable processor reservation, set SLOT_RESERVE in lsb.queues and
specify the reservation time (a job cannot hold any reserved slots after its
reservation time expires).
Syntax SLOT_RESERVE=MAX_RESERVE_TIME[n].
where n is an integer by which to multiply MBD_SLEEP_TIME.
MBD_SLEEP_TIME is defined in
lsb.params; the default value is 60 seconds.
Example Begin Queue
.
PJOB_LIMIT=1
SLOT_RESERVE = MAX_RESERVE_TIME[5]
.
End Queue
In this example, if MBD_SLEEP_TIME is 60 seconds, a job can reserve job slots for
5 minutes. If MBD_SLEEP_TIME is 30 seconds, a job can reserve job slots for 5
*30= 150 seconds, or 2.5 minutes.
Viewing information about reserved job slots
Reserved slots can be displayed with the bjobs command. The number of reserved
slots can be displayed with the
bqueues, bhosts, bhpart, and busers commands.
Look in the
RSV column.
Reserving Memory for Pending Parallel Jobs
By default, the rusage string reserves resources for running jobs. Because resources
are not reserved for pending jobs, some memory-intensive jobs could be pending
indefinitely because smaller jobs take the resources immediately before the larger
jobs can start running. The more memory a job requires, the worse the problem is.
Memory reservation for pending jobs solves this problem by reserving memory as
it becomes available, until the total required memory specified on the
rusage string
is accumulated and the job can start. Use memory reservation for pending jobs if
memory-intensive jobs often compete for memory with smaller jobs in your cluster.
Unlike slot reservation, which only applies to parallel jobs, memory reservation
applies to both sequential and parallel jobs.