Introduction to supercomputing at JSC - Theory and Practice

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Quiz - Day 3

You have submitted a job to a compute node, but it's very slow. What could be the reason?*

Another user is taking up the resources on this compute node and slowing my code down. Solution: write email to SC support, they can and will restrict the competing user.

My software is using more RAM (memory) that is available on this compute node and starts swapping. Solution: verify on LLView, reduce the memory or use more resources/compute nodes.

Something is not okay with the compute nodes/filesystem. Solution: check JSC status page, if there is an issue with resources used, wait till it is resolved.

Your software does not write the expected output but you haven't reached your available memory limit on the file system yet. What could be the reason?*

I have reached the inode limit. Solution: I need to reduce the number of files I have.

I have reached the maximum I/O limit for this (and next) month. Solution: I have to wait till next month to write more data files.

My application does not enter or crashes in the I/O routine after the latest software modifications. Solution: debug the software.

Mark all incorrect statements*

To make code compile as fast as possible on the login node do: make -j

The time asked for in the SLURM script (--time= ) is the time subtracted from the computing time budged, independent of how long the job actually ran.

When all core-h from the 3-month window (for normal compute time projects, not fixed contigent ones) are used, no job will run until the next month

I’m having a software/hardware issue when I use JSC system/s. What should I do?*

Check status page, check LLView

Read documentation, brainstorm, and try possible solutions. If nothing about the issue is found, contact SC support or your mentor.

Immediately log out and wait for 1 hour before logging in again.

HPC systems are overheated and admins need to ventilate them to bring fresh air. Be patient.

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