Platform LSF Administration Guide Version 6.2

CPU Time and Run Time Normalization
Administering Platform LSF
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CPU Time and Run Time Normalization
To set the CPU time limit and run time limit for jobs in a platform-independent way,
LSF scales the limits by the CPU factor of the hosts involved. When a job is dispatched
to a host for execution, the limits are then normalized according to the CPU factor of
the execution host.
Whenever a normalized CPU time or run time is given, the actual time on the execution
host is the specified time multiplied by the CPU factor of the normalization host then
divided by the CPU factor of the execution host.
If ABS_RUNLIMIT=Y is defined in
lsb.params, the run time limit is not normalized
by the host CPU factor. Absolute wall-clock run time is used for all jobs submitted with
a run limit.
Normalization host
If no host or host model is given with the CPU time or run time, LSF uses the default
CPU time normalization host defined at the queue level (DEFAULT_HOST_SPEC in
lsb.queues) if it has been configured, otherwise uses the default CPU time
normalization host defined at the cluster level (DEFAULT_HOST_SPEC in
lsb.params) if it has been configured, otherwise uses the submission host.
Example CPULIMIT=10/hostA
If hostA has a CPU factor of 2, and hostB has a CPU factor of 1 (hostB is slower
than
hostA), this specifies an actual time limit of 10 minutes on hostA, or on any other
host that has a CPU factor of 2. However, if
hostB is the execution host, the actual time
limit on
hostB is 20 minutes (10 * 2 / 1).
Normalization hosts for default CPU and run time limits
The first valid CPU factor encountered is used for both CPU limit and run time limit.
To be valid, a host specification must be a valid host name that is a member of the LSF
cluster. The CPU factor is used even if the specified limit is not valid.
If the CPU and run limit have different host specifications, the CPU limit host
specification is enforced.
If no host or host model is given with the CPU or run time limits, LSF determines the
default normalization host according to the following priority:
1 DEFAULT_HOST_SPEC is configured in lsb.queues
2 DEFAULT_HOST_SPEC is configured in lsb.params
3 If DEFAULT_HOST_SPEC is not configured in lsb.queues or lsb.params,
host with the largest CPU factor is used.
CPU time display (bacct, bhist, bqueues)
Normalized CPU time is displayed in the output of bqueues. CPU time is not
normalized in the output if
bacct and bhist.