HP-MPI Version 2.3.1 for Linux Release Note

4.18 Increasing the nofile Limit
The nofile limit on large Linux clusters needs to be increased in /etc/security/
limits.conf
* soft nofile 1024
For larger clusters, HP recommends a setting of at least:
• 2048 for clusters of 1900 cores or fewer
• 4096 for clusters of 3800 cores or fewer
• 8192 for clusters of 7600 cores or fewer
4.19 Using appfiles on HP XC Quadrics
To use appfiles on HP XC Quadrics clusters, set MPI_USESRUN=1. The appfile can only
differ in host name and rank count.
4.20 Using MPI_Bcast on Quadrics
On Quadrics interconnected clusters, the repeated use of MPI_Bcast within a tight
loop can cause an application to fail with the following Elan trap message:
ELAN TRAP - 0 0 CPROC - Bad Trap
Status=lbb40005 CommandProcSendTransExpected Command=200000201
Setting the environment variable LIBELAN_GROUP_SANDF=0 disables the latest “Store
and Forward” broadcast optimization from Quadrics while preserving all the other
optimized collectives.
4.21 MPI_Issend Call Limitation on Myrinet MX
Some earlier versions of Myrinet MX have a known resource limitation involving
outstanding MPI_Issend() calls. If more than 128 MPI_Issend() calls are issued
and not yet matched, further MX communication can hang. The only known
workaround is to have your application issue less than 128 unmatched MPI_Issend()
calls at a time. This limitation is fixed in versions 1.1.8 and later.
4.22 Terminating Shells
When a foreground HP-MPI job is run from a shell window, if the shell is terminated,
the shell sends signal SIGHUP to the mpirun process and its underlying ssh processes,
thus killing the entire job.
When a background HP-MPI job is run and the shell is terminated, the job might
continue depending on the actual shell used. For /bin/bash, the job is killed. For
/bin/sh and /bin/ksh, the job continues. If nohup is used when launching the job,
only background ksh jobs can continue. This behavior might vary depending on your
system.
4.18 Increasing the nofile Limit 31