FWIW: during MPI_Init, each process “publishes” all of its interfaces. Each
process receives a complete map of that info for every process in the job. So
when the TCP btl sets itself up, it attempts to connect across -all- the
interfaces published by the other end.
So it doesn’t matter what hos
Ok I figured, i'm going to have to read some more for my own curiosity. The
reason I mention the Resource Manager we use, and that the hostnames given but
PBS/Torque match the 1gig-e interfaces, i'm curious what path it would take to
get to a peer node when the node list given all match the 1gig
Right I understand those are TCP interfaces, I was just showing that I have two
TCP interfaces over one physical interface, so why I was asking how TCP
interfaces were selected. It rarely if ever will mater to us.
Brock Palen
www.umich.edu/~brockp
CAEN Advanced Computing
XSEDE Campus Champion
b
Ralph is right: OMPI aggressively uses all Ethernet interfaces by default.
This short FAQ has links to 2 other FAQs that provide detailed information
about reachability:
http://www.open-mpi.org/faq/?category=tcp#tcp-multi-network
The usNIC BTL uses UDP for its wire transport and actually
