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Night of the Lepus - A Plan 9 Perspective on Blue Gene’s Interconnects

By: Charles Forsyth, Jim McKie, Ron Minnich and Eric Van Hensbergen.


The nodes of a Blue Gene supercomputer are connected by five networks, four of unusual design. Only the I/O nodes have a conventional IP-based Ethernet. Plan 9ds internal and external representations of networks is simple and clean yet powerful enough to encompass those networks directly, without having to emulate existing network types. In supercom­ puter environments, applications often use the network hardware directly, but that makes it hard or impossible to share. We wish system services to make good use of the specialized networks too, in order to build fault-tolerant distributed services. Our kernel must therefore medi­ ate access to those networks, just as it does for IP traffic.