Improving NAMD scaling on Ranger

[pdblood]

Here are the environment variables that improve scaling of NAMD on
Ranger by 15-30%. This only works for mvapich 1, it does *not* work
with mvapich 2. I have tested these with mvapich 1.0.1. Set these in
your batch script before invoking ibrun:

export VIADEV_SMP_EAGERSIZE=64
export VIADEV_SMPI_LENGTH_QUEUE=256
export VIADEV_ADAPTIVE_RDMA_LIMIT=0
export VIADEV_RENDEZVOUS_THRESHOLD=50000

See this webpage for my benchmarks and scripts for running NAMD on
Ranger, Kraken, and Abe:

https://portal.teragrid.org/web/user-support/namd_benchmark