Administering Platform LSF - SAS

Chapter 17
Reserving Resources
Using memory reservation for pending jobs
Use the rusage string in the -R option to bsub or the RES_REQ parameter in
lsb.queues to specify the amount of memory required for the job. Submit the
job to a queue with RESOURCE_RESERVE configured.
See “Examples” on page 274 for examples of jobs that use memory reservation.
How memory reservation for pending jobs works
Amount of
memory reserved
The amount of memory reserved is based on the currently available memory
when the job is pending. For example, if LIM reports that a host has 300 MB
of memory available, the job submitted by the following command:
% bsub -R "rusage[mem=400]" -q reservation my_job
will be pending and reserve the 300 MB of available memory. As other jobs
finish, the memory that becomes available is added to the reserved memory
until 400 MB accumulates, and the job starts.
No memory is reserved if no job slots are available for the job because the job
could not run anyway, so reserving memory would waste the resource.
Only memory is accumulated while the job is pending; other resources
specified on the rusage string are only reserved when the job is running.
Duration and decay have no effect on memory reservation while the job is
pending.
How long memory is reserved (MAX_RESERVE_TIME)
Reserved memory expires at the end of the time period represented by the
number of dispatch cycles specified by the value of MAX_RESERVE_TIME set
on the RESOURCE_RESERVE parameter. If a job has not accumulated enough
memory to start by the time MAX_RESERVE_TIME expires, it releases all its
reserved memory so that other pending jobs can run. After the reservation time
expires, the job cannot reserve slots or memory for one scheduling session, so
other jobs have a chance to be dispatched. After one scheduling session, the
job can reserve available resources again for another period specified by
MAX_RESERVE_TIME.
Administering Platform LSF 273