LSF Version 7.3 - Administering Platform LSF

How Fairshare Affects Job Dispatch Order
300 Administering Platform LSF
RUN_JOB_FACTOR The job slots weighting factor.
Default: 3
HIST_HOURS Interval for collecting resource consumption history
Default: 5
How Fairshare Affects Job Dispatch Order
Within a queue, jobs are dispatched according to the queue’s scheduling policy.
◆ For FCFS queues, the dispatch order depends on the order of jobs in the queue
(which depends on job priority and submission time, and can also be modified
by the job owner).
◆ For fairshare queues, the dispatch order depends on dynamic share priority,
then order of jobs in the queue (which is not necessarily the order in which they
are submitted to the queue).
A user’s priority gets higher when they use less than their fair share of the cluster’s
resources. When a user has the highest priority, LSF considers one of their jobs first,
even if other users are ahead of them in the queue.
If there are only one user’s jobs pending, and you do not use hierarchical fairshare,
then there is no resource contention between users, so the fairshare policies have no
effect and jobs are dispatched as usual.
Job dispatch order among queues of equivalent priority
The order of dispatch depends on the order of the queues in the queue
configuration file. The first queue in the list is the first to be scheduled.
Jobs in a fairshare queue are always considered as a group, so the scheduler attempts
to place all jobs in the queue before beginning to schedule the next queue.
Jobs in an FCFS queue are always scheduled along with jobs from other FCFS
queues of the same priority (as if all the jobs belonged to the same queue).
Example In a cluster, queues A, B, and C are configured in that order and have equal queue
priority.
Jobs with equal job priority are submitted to each queue in this order: C B A B A.
◆ If all queues are FCFS queues, order of dispatch is C B A B A (queue A is first;
queues B and C are the same priority as A; all jobs are scheduled in FCFS
order).
◆ If all queues are fairshare queues, order of dispatch is AA BB C (queue A is first;
all jobs in the queue are scheduled; then queue B, then C).
◆ If A and C are fairshare, and B is FCFS, order of dispatch is AA B B C (queue A
jobs are scheduled according to user priority; then queue B jobs are scheduled
in FCFS order; then queue C jobs are scheduled according to user priority)
◆ If A and C are FCFS, and B is fairshare, order of dispatch is C A A BB (queue A
is first; queue A and C jobs are scheduled in FCFS order, then queue B jobs are
scheduled according to user priority)