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Last modified by valad on 2024/05/28 10:16
From version 4.1
edited by valad
on 2024/05/28 10:09
Change comment: There is no comment for this version
To version 2.1
edited by Thomas Coelho
on 2023/02/27 14:52
Change comment: There is no comment for this version

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17 17  == Infiniband ==
18 18  
19 19  The 'itp'-, 'itp-big'-, 'dfg-xeon'-, 'iboga'-, 'dreama'- and 'barcelona'-nodes have Infiniband Network. It is used by default when using our openMPI installation. Infiniband provides high bandwith with low latency. It can transport 20 GB/s with latency of 4 µs. In comparison, normal Gigabit Ethernet provides 1 GB/s with at least 30 µs latency. Latency is the time a data packet needs to travel from the source to its target. This is the main drawback when using Gigibit Ethernet for MPI communication.
20 -
21 -= Mellanox HPCX =
22 -
23 -Mellanox is the manufacturer of our Infiniband hardware. They provide an optimized set of libraries for running parallel programs.
24 -
25 -With the recent update to Ubuntu 18.04 some programs failed with the system default openMPI library. As alternative we have installed a system wide HPCX software.
26 -
27 -This lives in
28 -
29 - /home/software/hpcx/current .
30 -
31 -This points to the latest installed version.
32 -
33 -To use this library you have to extend your .bashrc. Include the following lines:
34 -
35 - export HPCX_HOME=/home/software/hpcx/current
36 - source $HPCX_HOME/hpcx-init.sh
37 -
38 -This doesn't change your actual environment yet. To finally activate the setup call:
39 -
40 - hpcx_load
41 -
42 -Then all MPI tools are loaded from HPCX. This is required for building and running. You may call this is in your jobs-scripts.
43 -
44 -There are other MPI flavours in HPCX. Read the documentation within there:
45 -
46 - /home/software/hpcx/current/README.txt
47 -