LSF Version 7.3 - Platform LSF Configuration Reference

LSB_MCPU_HOSTS

Syntax

LSB_MCPU_HOSTS="host_nameA num_processors1 host_nameB num_processors2..."

Description

Contains a list of the hosts and the number of CPUs used to run a job.

Valid values

num_processors1, num_processors2,... refer to the number of CPUs used on

host_nameA, host_nameB,..., respectively

Default

Not defined

Notes

The environment variables LSB_HOSTS and LSB_MCPU_HOSTS both contain the same

information, but the information is presented in different formats. LSB_MCPU_HOSTS uses

a shorter format than LSB_HOSTS. As a general rule, sbatchd sets both these variables.

However, for some parallel jobs, LSB_HOSTS is not set.

For parallel jobs, several CPUs are used, and the length of LSB_HOSTS can become very long.

sbatchd needs to spend a lot of time parsing the string. If the size of LSB_HOSTS exceeds 4096

bytes, LSB_HOSTS is ignored, and sbatchd sets only LSB_MCPU_HOSTS.

To verify the hosts and CPUs used for your dispatched job, check the value of LSB_HOSTS

for single CPU jobs, and check the value of LSB_MCPU_HOSTS for parallel jobs.

Where defined

Set by sbatchd before starting a job on the execution host

Example

When the you submit a job with the -m and -n options of bsub, for example,

% bsub -m "hostA hostB" -n 6 job

sbatchd sets the environment variables LSB_HOSTS and LSB_MCPU_HOSTS as follows:

LSB_HOSTS= "hostA hostA hostA hostB hostB hostB"

LSB_MCPU_HOSTS="hostA 3 hostB 3"

Both variables are set in order to maintain compatibility with earlier versions.