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

Einstein Toolkit trac-noreply at einsteintoolkit.org
Tue Dec 15 04:31:05 CST 2015


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

 The issue is sometimes that there are things that run before
 SystemTopology and hwloc have had a chance to set affinity, eg MPI_INIT
 which itself may for example allocate memory which is then bound to the
 "wrong" core. If I remember correctly, then there is a ticket/email thread
 somewhere in which Erik suggests adding a pre-MPI_INIT hook to the flesh
 so that SystemTopology can set affinity early. Note that this has to
 happen (as the thread explains) before parameter files are parsed since
 one cannot access argv before MPI_INIT so in particular it will ignore
 ActiveThorns settings in parfiles.

-- 
Ticket URL: <https://trac.einsteintoolkit.org/ticket/1850#comment:5>
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