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Task #2796

clarify what mdrun -cpt means

Added by Mark Abraham about 1 month ago. Updated 15 days ago.

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New
Priority:
Low
Assignee:
-
Category:
mdrun
Target version:
-
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uncategorized
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Description

For about a decade, mdrun has written a checkpoint every step when the period is set to 0. If that is intended, we should document that in e.g. mdrun -h, but I can't think of a use for it.

If that is not useful, or perhaps was once useful for debugging, we could remove it. Or if it's useful for development only, use an environment variable to set a constant in checkpointhandler.cpp

History

#1 Updated by Berk Hess about 1 month ago

That is intended, I would think. The documentation says you have to set -cpi -1 to turn it off, so 0 writing every step seems expected to me.

#2 Updated by Mark Abraham about 1 month ago

Berk Hess wrote:

That is intended, I would think. The documentation says you have to set -cpi -1 to turn it off, so 0 writing every step seems expected to me.

OK, but what value would that have? It means we've got an extra thing to document, and an extra conditional to check every MD step.

#3 Updated by Berk Hess about 1 month ago

I don't understand what you mean, but I have not checked the exact behavior. I don't want additional code behavior. Maybe you mean "every step" vs "every nstlist" steps? I would like 0 to mean as often as reasonably possible, which I guess would mean every nstlist steps.

#4 Updated by Mark Abraham 15 days ago

Berk Hess wrote:

I don't understand what you mean, but I have not checked the exact behavior. I don't want additional code behavior. Maybe you mean "every step" vs "every nstlist" steps? I would like 0 to mean as often as reasonably possible, which I guess would mean every nstlist steps.

The code checks every MD step whether the period is zero, and if it is zero, it signals to write a checkpoint. Currently in mdlib/checkpointhandler.cpp, but the logic has been the same for a very long time.

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