[O-MPI devel] pml vs bml vs btl

[Brad Penoff]

Greetings,

I was just curious about the distinction between the pml, bml, and btl 
layers within OpenMPI and was wondering if there was any place (other than 
the code ;-) where I could read about the design decisions.  Any pointers?

Particularly, I'm just curious about the difference between pml-bml-btl 
and the old pml-ptl (as described in your TEG paper) and why changes 
were made.  I'm also trying to understand the differences between this 
approach and LAM's RPI as well as the device-channel distinction made in 
MPICH2; could anyone recommend something I could read or give me a brief 
description here to satisfy my curiosities?

Thanks,
brad