[ET Trac] [Einstein Toolkit] #921: Automatic undersubscribing

[Einstein Toolkit]

#921: Automatic undersubscribing
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  Reporter:  hinder       |       Owner:  eschnett
      Type:  enhancement  |      Status:  new     
  Priority:  minor        |   Milestone:          
 Component:  SimFactory   |     Version:          
Resolution:               |    Keywords:          
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Comment (by eschnett):

 The current behaviour does not assume that you are running on only a
 single node. It works as follows:
 - user requests N cores (via --procs)
 - system granularity is determined (e.g. can allocate only integer number
 of nodes) (depends on --ppn-used)
 - if necessary, N is rounded up

 What you suggest is to modify the value specified via --ppn-used instead
 of the value specified via --procs. Or are you suggesting to do this only
 if at most a single node is allocated? Or do you suggest to not round up
 at all, and leave some cores unused?

 The intention behind rounding up is that you will have to pay for these
 cores anyway, so you may as well use them. Whether this is correct very
 likely doesn't depend on the PPN of the system you use. In a production
 run, you probably want to use the additional cores (why not?), in a
 benchmark you don't. But then, in a benchmark you probably need to be
 aware of the node configuration anyway, so you may as well specify --ppn-
 used.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/921#comment:1>
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