Craig,
Let me look at your script, if you'd like... I may be able to help
there. I've also been seeing some "interesting results for WRF on
OpenMPI, and we may want to see if we're taking complimentary approaches...
gerry
Craig Tierney wrote:
A followup....
Part of problem was affinity. I had written a script to do processor
and memory affinity (which works fine with MVAPICH2). It is an
idea that I got from TACC. However, the script didn't seem to
work correctly with OpenMPI (or I still have bugs).
Setting --mca mpi_paffinity_alone 1 made things better. However,
the performance is still not as good:
Cores Mvapich2 Openmpi
---------------------------
8 17.3 17.3
16 31.7 31.5
32 62.9 62.8
64 110.8 108.0
128 219.2 201.4
256 384.5 342.7
512 687.2 537.6
The performance number is GFlops (so larger is better).
The first few numbers show that the executable is the right
speed. I verified that IB is being used by using OMB and
checking latency and bandwidth. Those numbers are what I
expect (3GB/s, 1.5mu/s for QDR).
However, the Openmpi version is not scaling as well. Any
ideas on why that might be the case?
Thanks,
Craig
Craig Tierney wrote:
I am running openmpi-1.3.3 on my cluster which is using
OFED-1.4.1 for Infiniband support. I am comparing performance
between this version of OpenMPI and Mvapich2, and seeing a
very large difference in performance.
The code I am testing is WRF v3.0.1. I am running the
12km benchmark.
The two builds are the exact same codes and configuration
files. All I did different was use modules to switch versions
of MPI, and recompiled the code.
Performance:
Cores Mvapich2 Openmpi
---------------------------
8 17.3 13.9
16 31.7 25.9
32 62.9 51.6
64 110.8 92.8
128 219.2 189.4
256 384.5 317.8
512 687.2 516.7
The performance number is GFlops (so larger is better).
I am calling openmpi as:
/opt/openmpi/1.3.3-intel/bin/mpirun --mca plm_rsh_disable_qrsh 1 --mca btl
openib,sm,self \
-machinefile /tmp/6026489.1.qntest.q/machines -x LD_LIBRARY_PATH -np $NSLOTS
/home/ctierney/bin/noaa_affinity ./wrf.exe
So,
Is this expected? Are some common sense optimizations to use?
Is there a way to verify that I am really using the IB? When
I try:
-mca bta ^tcp,openib,sm,self
I get the errors:
--------------------------------------------------------------------------
No available btl components were found!
This means that there are no components of this type installed on your
system or all the components reported that they could not be used.
This is a fatal error; your MPI process is likely to abort. Check the
output of the "ompi_info" command and ensure that components of this
type are available on your system. You may also wish to check the
value of the "component_path" MCA parameter and ensure that it has at
least one directory that contains valid MCA components.
--------------------------------------------------------------------------
But ompi_info is telling me that I have openib support:
MCA btl: openib (MCA v2.0, API v2.0, Component v1.3.3)
Note, I did rebuild OFED and put it in a different directory
and did not rebuild OpenMPI. However, since ompi_info isn't
complaining and the libraries are available, I am thinking that
is isn't a problem. I could be wrong.
Thanks,
Craig
--
Gerry Creager -- gerry.crea...@tamu.edu
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983
Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843
