Each time LSF attempts to dispatch a job, it checks to see which hosts are eligible to run the job. A number of conditions determine whether a host is eligible:
Host dispatch windows
Resource requirements of the job
Resource requirements of the queue
Host list of the queue
Host load levels
Job slot limits of the host
User quota and user limits
A host is only eligible to run a job if all the conditions are met. If a job is queued and there is an eligible host for that job, the job is placed on that host. If more than one host is eligible, the job is started on the best host based on both the job and the queue resource requirements.
A host is available if the values of the load indices (such as r1m, pg, mem) of the host are within the configured scheduling thresholds. There are two sets of scheduling thresholds: host and queue. If any load index on the host exceeds the corresponding host threshold or queue threshold, the host is not eligible to run any job.
When LSF tries to place a job, it obtains current load information for all hosts.
The load levels on each host are compared to the scheduling thresholds configured for that host in the Host section of lsb.hosts, as well as the per-queue scheduling thresholds configured in lsb.queues.
If any load index exceeds either its per-queue or its per-host scheduling threshold, no new job is started on that host.