Scheduling Policy on BlueGene/L


LoadLeveler is used as scheduling system on the machine.

Job Classes

LoadLeveler is configured with the following classes and limits (ordered by descending priority):

Class Name Max. Runtime Default Runtime Max. Jobs Max. Jobs per User Running on BasePartition
n8192 24:00:00 06:00:00 1 - all
n4096  24:00:00 06:00:00 2 - all except R000, R001
n2048  24:00:00 06:00:00 4 - all except R000
n1024 24:00:00 06:00:00 8 - all except R000
n0512 24:00:00 06:00:00 5 - all except R000
small 00:30:00 00:30:00 32 2 R000
nocsmall 00:30:00 00:30:00 1 1 R000

The job class is automatically enforced by LoadLeveler depending on the size of a job. The scheduler prioritizes the idle jobs regarding to the class priority, the job submission time, the users quota, and the number of jobs a user has already running.

The scheduler runs the job with the highest priority if the necessary resources are available. If the requested resources are not yet available the scheduler uses a backfilling strategy to run lower priority, short duration jobs on any available resources as long as doing so will not delay the starting of the highest priority job.


Displaying Current Load

LLview - our monitoring GUI - has now been adapted to the usage of LoadLeveler as scheduling system. It displays the current load of the system and a graphical chart of the queued jobs giving a rough prediction of the future load of the system.
Usage:

    on JUBL:   llview
    on JUMP:   llview_bgl     (restricted access, see llview for BG/L)

The command

    on JUBL:   llstat
will also list the current load of the system and the job queue.

last change 01.03.2007 | Michael Stephan | Print