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Using the /etc/poe.limits File

The /etc/poe.limits file is optional and it enables the system administrator to override the default values for certain POE environment variables. This is useful in cases where the environment variable default values might cause problems on a particular node. For example, if a node had only 64M of real memory, the default value of 64M for MP_BUFFER_MEM would be too high. To correct this problem, the system administrator would specify a lower value for MP_BUFFER_MEM in the /etc/poe.limits file on that node.

Entries in the /etc/poe.limits File

Entries in the /etc/poe.limits file must be in the form:

supported_object = value

where supported_object is currently limited to the following:

Note:
Any line in the file with the character # or ! in the first column is treated as a comment.

Handling of /etc/poe.limits by the Partition Manager Daemon (pmdv3)

If the /etc/poe.limits file has been set up on a particular node, the Partition Manager daemon (pmdv3) on that node:

  1. Compares the values specified in the /etc/poe.limits file against the environment variables received from the home node
  2. If necessary, resets the environment variables as follows:

    MP_BUFFER_MEM
    If the value in the environment exceeds the value specified in /etc/poe.limits, pmdv3 resets the value to that in /etc/poe.limits.

    MP_USE_LL

    If the value in the file is set to yes and POE determines that the job is not being run under LoadLeveler, the job is terminated. Setting the value to no has no effect.

  3. If a supported_object is specified in /etc/poe.limits but is not set in the environment, sets the value to that specified in /etc/poe.limits
Note:
If the /etc/poe.limits file contains any entries either with unsupported objects to the left of the equal sign or with invalid (non-numeric for MP_BUFFER_MEM) values to the right, pmdv3 flags these entries in the pmdlog for that node. pmdv3 also uses the pmdlog to indicate when a supported_object has been set or reset in the environment.


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