> it appears that 1.8 is much faster than 1.6.5 with the default settings, but slower when you set btl=tcp,self?
Precisely. However, with the default settings both versions are much slower compared to other MPI distributions such as MPICH, MVAPICH, and proprietary ones. The 'btl=tcp,self' setting substantially boost performance of 1.6.5 on single processor multi-core computers running under Linux, or Mac OS X. But it doesn't work in 1.8 anymore ...
> Is this a copy/paste error?
Unfortunately, it is not a copy/paste error.
> the next question is: how many nodes were in your allocation?
2 processes on a single machine running under Ubuntu Linux (laptop), or Mac OS X (Mac mini).
With best regards,