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Opened 5 years ago

Last modified 5 years ago

#1528 new task

check that mainstream machines use correct thread binding

Reported by: Roland Haas Owned by: Erik Schnetter
Priority: major Milestone:
Component: SimFactory Version: development version
Keywords: Cc:

Description

it is possible that systems that initialize themselves before hwloc (eg MPI) bind to the wrong CPU core unless (the equivalent of) numactl is used.

For an example on bluewaters see #1527.

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Change History (4)

comment:1 Changed 5 years ago by Erik Schnetter

This had a significant performance impact on Blue Waters (from 14 M/hr to 17 M/hr).

comment:2 Changed 5 years ago by Erik Schnetter

We need to check the following systems:

  • bluewaters (done)
  • carver
  • datura
  • gordon
  • hopper (done)
  • lonestar
  • mike (done)
  • orca
  • pandora
  • philip
  • queenbee
  • shelob (done)
  • stampede (done)
  • stampede-mic
  • titan (done)
  • trestles
  • vesta
  • zwicky

Please edit this text, appending e.g. "(done)" when a machine has been checked.

Last edited 5 years ago by Erik Schnetter (previous) (diff)

comment:3 Changed 5 years ago by Ian Hinder

Can hwloc be given a parameter to abort with an error message if the thread binding is not correct? If it doesn't know what should be correct, this could be passed in using some environment variables. This would simplify the testing.

comment:4 Changed 5 years ago by Erik Schnetter

Yes, such a parameter would be possible. It is in general not clear (without experimentation) which thread bindings are optimal, but we can flag the really bad cases where processes are not bound to the correct socket.

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