The PFEs enable quick turnaround for tasks such as file editing, file transfer, compiling, and short debugging/testing sessions, as well as for PBS batch job submissions via PBS to the Aitken, Electra, or Endeavour compute nodes.

To support the availability and reliability of the PFEs for all users, resource-intensive tasks should be submitted to the compute nodes, not run on the PFEs. Therefore, the PFEs have the following default usage quotas:

• Hard quota limits for each user are 4 cores for CPU usage and 8 gigabytes (GB) for memory usage.
• Soft quota limits for each user are 2 cores for CPU usage and 4 GB of memory usage.

If your processes running on a PFE exceed the default usage limits, the memory and CPU resources available to you on the PFE will be reduced for a period of time, and you will be notified via email.

Email Notifications and Consequences

If you exceed the soft quota usage limits on a PFE for more than 30 minutes, the memory and CPU resources available to you on that PFE will be reduced by 20% for a 30-minute period. During this time, your CPU processes will be throttled, and processes exceeding the memory limit will be terminated.

Resource availability will return to normal after 30 minutes. However, if you exceed the soft quota limits again within a three-hour window, the memory and CPU resources available to you on the PFE will be reduced further—by 50% this time—and the three-hour timer will reset. If you exceed the soft quota limits a third time, the resources available to you on the PFE will be reduced by 70%.

Each time this happens, you will receive an email notification that provides usage details for all of your processes running on the PFE. To stay within the quota limits, consider stopping any resource-intensive processes listed in the email; these processes should instead be run on a Pleiades, Aitken, or Electra compute node via a PBS job submission.

Whitelisted Processes

Processes such as compilation and file transfers are whitelisted and will not count toward CPU quota limits. However, all processes are still counted toward memory quota limits.