Platform LSF Administration Guide Version 6.2

Configuring Preemptive Scheduling
Administering Platform LSF
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Configuring additional job slot limits for preemptive scheduling
The following job slot limits are always affected by preemptive scheduling:
◆ Total job slot limit for hosts, specified at the host level (SLOTS and HOSTS in
lsb.resources)
◆ Total job slot limit for individual users, specified at the user level (SLOTS and
USERS in
lsb.resources); by default, suspended jobs still count against the
limit for user groups
PREEMPT_FOR in
lsb.params
To configure additional job slot limits to be affected by preemptive scheduling, set
PREEMPT_FOR in
lsb.params, and use one or more of the following keywords to
indicate that suspended jobs do not count against that job slot limit:
◆ GROUP_MAX—total job slot limit for user groups, specified at the user level
(MAX_JOBS in
lsb.users); if preemptive scheduling is enabled, suspended jobs
never count against the limit for individual users
◆ HOST_JLU—total number of jobs for users and user groups, specified at the host
level (JL/U in
lsb.hosts)
◆ USER_JLP—user-processor job slot limit for individual users, specified at the user
level (JL/P in
lsb.users)
◆ GROUP_JLP—per-processor job slot limit for user groups, specified at the user
level (JL/P in
lsb.users)
Job slot limits specified at the queue level are never affected by preemptive scheduling.
Configuring preemptable queue preference
For preemptive queues, you can specify which preemptable queues are considered first
for preemption by configuring queue preference in the queue with the highest priority.
To indicate the order of preference for the preemptable queues, put a plus sign (
+) after
the names of the preemptable queues and a preference level as a positive integer. Higher
numbers indicate higher preferences for preempting a job in that queue. If no queue
preference is specified, it is assumed to be 0. If there are multiple queues, LSF preempts
jobs in the queue with the highest preference; queues at the same level of preference are
ordered by queue priority.
When preemtable queue preference is enabled, LSF considers jobs from preferred
queues first instead of choosing running jobs based on best hosts:
◆ Queues with a preference number are preferred over queues without a preference
number
◆ Queues with a higher preference number are preferred over queues with lower
preference number
◆ For queues without a preference number, the queue with lower-priority is preferred
than the queue with higher priority
Example Begin Queue
QUEUE_NAME = high_priority
PRIORITY = 50
PREEMPTION = PREEMPTIVE[low_q1+2 low_q2 low_q3]
End Queue