Information AboutMyrinet |
| CATEGORIES ABOUT MYRINET | |
| supercomputers | |
| SHOPPER'S DELIGHT | |
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Myrinet physically consists of two Fibre Optic cables, upstream and downstream, connected to the host computers with a single connector. Machines are connected via low-overhead Router s and Switch es, as opposed to connecting one machine directly to another. Myrinet includes a number of fault-tolerance features, mostly backed by the switches. These include flow control, error control, and "heartbeat" monitoring on every link. The first generation provided 512 Mbit/s data rates in both directions, and later versions supported 1.28 Gbit/s and 2 Gbit/s. Newest "Fourth-generation Myrinet" supports 10 Gbit/s data rate, and is interoperable with 10 Gigabit Ethernet on PHY , the physical layer (cables, connectors, distances, signaling). According to Myricom Fourth-generation Myrinet products are expected to start to ship in September 2005. Myrinet's throughput is close to the theoretical maximum of the physical layer. On the latest 2.0 Gbit/s links Myrinet often runs at 1.98 Gbit/s of sustained throughput, considerably better than what Ethernet offers, which varies from 0.6 and 1.9 Gbit/s depending on load. However, for supercomputing, the low latency of Myrinet is even more important than its throughput performance, since, according to Amdahl's Law , a high-performance parallel system tends to be bottlenecked by its slowest sequential process, which is often the latency of transmission of messages across the network in all but the most Embarrassingly Parallel supercomputer workloads. According to Myricom, 141 (28.2%) of the June-2005 TOP500 supercomputers use Myrinet technology, making it the most popular. {Link without Title} In the November 2005 TOP500, the number of supercomputers using Myrinet is down to 101 computers, or 20.2%. {Link without Title} SEE ALSO EXTERNAL LINKS |