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 processes 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 hosts with fast processors to have more jobs slots than the number of cores by setting the MXJ value for the given host to a fixed number of job slots. This enables the more powerful host to execute more jobs concurrently to take advantage of the processor’s speed.
To change the number of job slots on a grid node, follow these steps:
  1. Log on to the grid control server as the LSF Administrator (lsfadmin).
  2. 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
  3. Edit this file to specify the maximum number of job slots for all nodes or for each node. There are two ways you can do this.
    • To specify the total number of job slots per node, 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 slot per core for each node in the grid. You can replace this value with a number that specifies the maximum number of job slots on each node, regardless of the number of cores. For example, a value of ! on a machine with 16 cores results in 16 job slots, while a value of 2 on a machine with 16 cores results in just 2 job slots.
    • To specify the total number of jobs slots 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      16     ()      ()    ()     ()     ()            #Example
      D1235      16     ()      ()    ()     ()     ()            #Example
      D1236      16     ()      ()    ()     ()     ()            #Example
      D1237      16     ()      ()    ()     ()     ()            #Example
      D1238      16     ()      ()    ()     ()     ()            #Example
      End Host
      Each line designates the concurrent execution of 16 jobs on each node.
  4. Save and close the file.
  5. Verify the LSF batch configuration file by entering this command at the command prompt: badmin reconfig
  6. For details about using this command, see Platform LSF Reference.