Specifying Job Slots for Machines

Platform LSF uses job slots to specify the number of processes that are allowed to run concurrently on a machine. A machine cannot run more concurrent jobs than it has job slots. The default number of job slots for a machine is the same as the number of processor cores in the machine.

However, you can configure more than one job slot for each processor core. For machines with fast processors, configuring two jobs slots for each processor core enables you to take advantage of the processors' speed.

To change the number of job slots on a grid node, follow these steps:

Log on to the computer that hosts the grid controller as the LSF Administrator (lsfadmin).
Open the file lsb.hosts, which is located in the directory LSF-install-dir\conf\lsbatch\cluster-name\configdir. This is the LSF batch configuration file. Locate the Host section of the file, which contains an entry for a default grid node.
```
Begin
Host
HOST_NAME MXJ    r1m     pg    ls    tmp  DISPATCH_WINDOW  #Keywords
default    !     ()      ()    ()     ()     ()            #Example
End Host
```
Edit this file to specify the maximum number of job slots for all nodes or for each node.
- To specify the total number of job slots for all nodes, edit the line for the default node. Here is an example:
  Begin Host HOST_NAME MXJ r1m pg ls tmp DISPATCH_WINDOW #Keywords default ! () () () () () #Example End Host
  
  The value ! represents one job per processor for each node in the grid. You can replace this value with a number that represents the maximum number of job slots on each node.
- To specify the total number of job per node, add a line for each node in the grid. Here is an example:
  Begin Host HOST_NAME MXJ r1m pg ls tmp DISPATCH_WINDOW #Keywords default ! () () () () () #Example D1234 2 () () () () () #Example D1235 2 () () () () () #Example D1236 2 () () () () () #Example D1237 2 () () () () () #Example D1238 2 () () () () () #Example End Host
  Each line designates the concurrent execution of two jobs on each node.
Save and close the file.
Verify the LSF batch configuration file by entering this command at the command prompt: badmin reconfig
For details about using this command, see Platform LSF Reference.