LSF Version 7.3 - Administering Platform LSF
Tuning LIM
660 Administering Platform LSF
Tuning LIM
LIM provides critical services to all LSF components. In addition to the timely
collection of resource information, LIM provides host selection and job placement
policies. If you are using Platform MultiCluster, LIM determines how different
clusters should exchange load and resource information. You can tune LIM policies
and parameters to improve performance.
LIM uses load thresholds to determine whether to place remote jobs on a host. If
one or more LSF load indices exceeds the corresponding threshold (too many users,
not enough swap space, etc.), then the host is regarded as busy and LIM will not
recommend jobs to that host. You can also tune LIM load thresholds.
You can also change default LIM behavior and pre-select hosts to be elected master
to improve performance.
In this section
â—† Adjusting LIM Parameters on page 660
â—† Load Thresholds on page 660
â—† Changing Default LIM Behavior to Improve Performance on page 662
Adjusting LIM Parameters
There are two main goals in adjusting LIM configuration parameters: improving
response time, and reducing interference with interactive use. To improve response
time, tune LSF to correctly select the best available host for each job. To reduce
interference, tune LSF to avoid overloading any host.
LIM policies are advisory information for applications. Applications can either use
the placement decision from LIM, or make further decisions based on information
from LIM.
Most of the LSF interactive tools use LIM policies to place jobs on the network. LSF
uses load and resource information from LIM and makes its own placement
decisions based on other factors in addition to load information.
Files that affect LIM are
lsf.shared, lsf.cluster.cluster_name, where
cluster_name is the name of your cluster.
RUNWINDOW parameter
LIM thresholds and run windows affect the job placement advice of LIM. Job
placement advice is not enforced by LIM.
The RUNWINDOW parameter defined in
lsf.cluster.cluster_name specifies
one or more time windows during which a host is considered available. If the
current time is outside all the defined time windows, the host is considered locked
and LIM will not advise any applications to run jobs on the host.
Load Thresholds
Load threshold parameters define the conditions beyond which a host is considered
busy by LIM and are a major factor in influencing performance. No jobs will be
dispatched to a busy host by LIM’s policy. Each of these parameters is a load index
value, so that if the host load goes beyond that value, the host becomes busy.