UM version4.5 GCOM

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Comparing the use of different versions of GCOM with UM Version4.5

Preamble

Versions of GCOM are available from:

GCOMv3.1

  • Compatible with UMv4.5 without any code changes.
  • Principle benefit is a better all-to-all routine (used in gathering output data to the master process).

DDR Infiniband & Intel Harpertown

  • For Bristol's BlueCrystal-phase2 machine:
IMB ping-pong message latency
0 bytes 128 bytes 1024 bytes
between nodes ~3.0us ~3.8us ~6.0us


%time - 8x8 decomp.
subruotine GCOMv2.9b5 GCOMv3.1
gatherfield 12% ~5%
swapbounds 18% ~15%