On 7/26/06 5:55 PM, "Michael Kluskens" <mk...@ieee.org> wrote:
>> How is the message passing of Open-MPI implemented when I have >> say 4 nodes with 4 processors (SMP) each, nodes connected by a gigabit >> ethernet ?... in other words, how does it manage SMP nodes when I >> want to use all CPUs, but each with its own process. Does it take >> any advantage of the SMP at each node? > > Someone can give you a more complete/correct answer but I'll give you > my understanding. > > All communication in OpenMPI is handled via the MCA module (term?) We call them "components" or "plugins"; a "module" is typically an instance of those plugins (e.g., if you have 2 ethernet NICs with TCP interfaces, you'll get 2 instances -- modules -- of the TCP BTL component). > self - process communicating with itself > sm - ... via shared memory to other processes > tcp - ... via tcp > openib - ... via Infiniband OpenIB stack > gm & mx - ... via Myrinet GM/MX > mvapi - ... via Infiniband Mellanox Verbs All correct. > If you launch your process so that four processes are on a node then > those would use shared memory to communicate. Also correct. Just chiming in with verifications! :-) -- Jeff Squyres Server Virtualization Business Unit Cisco Systems
