HP-MPI Version 2.3.1 for Linux Release Note

Table Of Contents
during MPI message transfer. This results in slightly more memory being allocated,
but reduces the likelihood that a forked process writes to a page of memory that was
also being used for message transfer when a fork call occurred.
4.14 Disabling Fork Safety
Applications running on Linux systems with kernels earlier than 2.6.12 might display
the following warning message:
libibverbs: Warning: fork()-safety requested but init failed
This warning message appears because the HP-MPI library enabling the OFED 1.2 fork
safety feature is not supported by Linux kernels earlier than 2.6.12. It does not affect
the application run. To disable HP-MPI fork safety, set the environment variable
MPI_IBV_NO_FORK_SAFE, as in the following example:
% /opt/hpmpi/bin/mpirun -np 4 -prot -e MPI_IBV_NO_FORK_SAFE=1 \
-hostlist nodea,nodeb,nodec,noded /my/dir/hello_world
4.15 Using Fork with OFED
Applications using fork() might crash on configurations with InfiniBand using OFED
on kernels earlier than v2.6.18. You can avoid known problems with fork() and OFED
in any of the following ways:
Run on XC V3.2.1 or later, where all known OFED fork() fixes have been made.
Run on a system with kernel 2.6.18 or later.
Run InfiniBand with non-OFED drivers. (This option is not available on
configurations with ConnectX InfiniBand Host Channel Adapters where OFED is
required.)
4.16 Memory Pinning with OFED 1.2
The initial release of OFED 1.2 contains a bug that causes the memory pinning function
to fail after certain patterns of malloc and free. The symptom, which is visible from
HP-MPI, might be any of several error messages such as:
> prog.x: Rank 0:1: MPI_Get: Unable to pin memory for put/get
This bug has already been fixed in OFED 1.3, but if you are running with the initial
release of OFED 1.2, the only workaround is to set MPI_IBV_NO_FORK_SAFE=1.
4.17 Upgrading to OFED 1.2
When upgrading to OFED 1.2 from earlier versions, the installation script might not
stop the previous OFED version before uninstalling it. Therefore, stop the old OFED
stack before upgrading to OFED 1.2. For example:
/etc/init.d/openibd stop
30 Known Issues and Workarounds