Myrinet 2Gbps Networks(http://www.myri.com)

Overview• Myrinet is a high-performance, packet-communica

tion and switching technology that can be used to interconnect clusters of workstations, PCs, servers, or single-board computers.

• Cluster computing has the following advantages:– high performance– high availability

• Cluster computing needs:– High throughput bulk data transfer– Low latency message passing

Pictures of Myrinet

Myrinet’s Features• Full-duplex 2+2 Gigabit/second links, switch ports, and

interface ports• Flow control, error control, and "heartbeat" continuity

monitoring on every link• Low-latency, cut-through, crossbar switches, with

monitoring capability• Switch networks that can scale to tens of thousands of

hosts• Host interfaces that execute a control program to interact

directly with host processes ("OS bypass") for low-latency communication, and directly with the network to send, receive, and buffer packets

A Possible Configuration

Two computers can also beconnected directly througha cable.

Packet Format and Routing

An IP packet can be carried by a Myrinet packet as its payload.

Source routing

Deadlocks May Form• Source routing is used.

– A network mapping program needs to be run on one host to discover the map of the network. It then distributes the map to all other host interfaces.)

• Cut-through switching is used to reduce message latency. (wormhole routing)– For high-performance distributed application programs, latency

will be more important than throughput (because latency cannot be improved whereas throughput can be improved.)

• Thus deadlock situations may form.• Myrinet thus provides a monitoring and timeout mechanis

m to break deadlock situations.

Myrinet Host Interface

• We can write the firmware source code, compile it, download it, and run it on the host interface!!!!

1995 version

Myrinet Host Software

• Myrient can use zero-copy and checksum offload capabilities to improve transfer throughput.