I have a bunch of 8 GB memory nodes in a cluster who were lately
upgraded to 16 GB. When I run any jobs I get the following warning:
--------------------------------------------------------------------------
WARNING: It appears that your OpenFabrics subsystem is configured to
only
allow registering part of your physical memory. This can cause MPI jobs
to
run with erratic performance, hang, and/or crash.
This may be caused by your OpenFabrics vendor limiting the amount of
physical memory that can be registered. You should investigate the
relevant Linux kernel module parameters that control how much physical
memory can be registered, and increase them to allow registering all
physical memory on your machine.
See this Open MPI FAQ item for more information on these Linux kernel
module
parameters:
http://www.open-mpi.org/faq/?category=openfabrics#ib-locked-pages
Local host: comp022.local
Registerable memory: 8192 MiB
Total memory: 16036 MiB
Your MPI job will continue, but may be behave poorly and/or hang.
--------------------------------------------------------------------------
Searching for a fix to this issue, I found that I have to set
log_num_mtt within the kernel module, so I added this line to
modprobe.conf:
options mlx4_core log_num_mtt=21
But then ib0 interface fails to start showing this error:
ib_ipoib device ib0 does not seem to be present, delaying
initialization.
Reducing the value of log_num_mtt to 20, allows ib0 to start but shows
the registerable memory of 8 GB warning.
I am using OFED 1.3.1, I know it is pretty old and we are planning to
upgrade soon.
Output on all nodes for 'ompi_info -v ompi full --parsable':
ompi:version:full:1.2.7
ompi:version:svn:r19401
orte:version:full:1.2.7
orte:version:svn:r19401
opal:version:full:1.2.7
opal:version:svn:r19401
Any help would be appreciated.
Waleed Lotfy
Bibliotheca Alexandrina
