In LSF, a job slot is a basic unit of processor allocation. By default, each processor is a single job slot, which means that LSF executes only one job at a time on that processor. However, it is possible to configure more than one job slot per processor on a host-by-host basis. If the jobs that you are submitting are I/O intensive, you might want to try to configure two job slots per processor, especially if the processor is a fast one.

To change the number of job slots on a machine, perform these steps:

1. Log on to the machine as the LSF Administrator (lsfadmin).
2. Open the file lsb.hosts, which is located in the directory LSF-installation-directory\conf\lsbatch\cluster-name\configuration-directory. In the Host section of the file, you see an entry for a default host.

   Begin Host
   HOST_NAME MXJ r1m pg ls tmp DISPATCH_WINDOW #Keywords
   default ! () () () () () #Example
   End Host
   

   The value specifies one job per processor.
3. Edit this section by replacing the value ! with a number that specifies the number of jobs you want to run per processor. For example, if you want to run two jobs per processor, edit the Host section as follows:

   Begin Host
   HOST_NAME MXJ r1m pg ls tmp DISPATCH_WINDOW #Keywords 
   default 2 () () () () () #Example
   End Host
   

4. Save your changes, and close the file.
5. Issue the command badmin reconfig.

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