[ET Trac] [Einstein Toolkit] #1850: Severe performance problem on Stampede

[Einstein Toolkit]

#1850: Severe performance problem on Stampede
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  Reporter:  hinder      |       Owner:                     
      Type:  defect      |      Status:  review             
  Priority:  major       |   Milestone:                     
 Component:  SimFactory  |     Version:  development version
Resolution:              |    Keywords:                     
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Comment (by knarf):

 Replying to [comment:27 dradice@…]:
 > Activating SystemTopology would only be harmful if the user is running
 multiple independent Cactus simulations on the same workstation. In that
 case, SystemTopology would place all Cactus instances on the same core and
 degrade performances significantly.

 That is like - when running testsuites in parallel. I don't do that often
 though, but we did develop a script for it once. What would happen if
 SystemTopology isn't used in that case - the OS would distribute the
 processes, wouldn't it?

 Would it be reasonable to let SystemTopology (by default) not enforce
 pinning when using "less than one full node"? Would it even be possible to
 always detect that situation correctly? Would not using SystemTopology in
 that case mean a performance hit? If so, how big would it probably be?

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/1850#comment:28>
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