[Pw_forum] Wall time vs. CPU time

[Vo, Trinh (388C)]

Dear PWSCF users,

For all my jobs, the wall time is usually significantly larger than the CPU time.  Especially the larger the job, the larger the difference.  For example, for a large  job run for a system of 824 electrons, I  have

1d   15h58m CPU time,        2d    7h44m wall time

I am using QE-4.1.2 and run on 40CPUs (each CPU has 3 tasks).  Linux x86_64, and Intel Compiler 10.1.015.

I don’t know what are the possible reasons that causes this delay.  What factors I should look at to fix this problem.

Thank you very much,


Trinh Vo
CalTech
Jet Propulsion Lab
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