1 / 15

An Overview of Myrinet

An Overview of Myrinet. By: Ralph Zajac. What is Myrinet?. LAN designed for clusters Based on USCD’s ATOMIC LAN Has many characteristics of MPP message-passing networks. MPP Network Characteristics. High data rate Regular topology and scalability Very low error rate Cut-through routing

damisi
Télécharger la présentation

An Overview of Myrinet

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. An Overview of Myrinet By: Ralph Zajac

  2. What is Myrinet? • LAN designed for clusters • Based on USCD’s ATOMIC LAN • Has many characteristics of MPP message-passing networks

  3. MPP Network Characteristics • High data rate • Regular topology and scalability • Very low error rate • Cut-through routing • Flow control

  4. ATOMIC LAN: Overview • Based on technology from Caltech’s Mosaic project • Used TCP/IP at burst rates of 400 Mb/s • Error rate less than 10-15

  5. ATOMIC LAN: Limitations • Asynchronous communication could lead to deadlock • Network topology • Complex • Hidden computing power • Performance limited by lack of DMA in host interface • End-to-end data rates limited by TCP/IP stack of OS

  6. Myrinet • Designed to address the limitations of ATOMIC LAN • Not limited to an existing MPP network • Specifications published in ANSI/VITA 26-1998

  7. Myrinet: Links • Can be copper (up to 25m) or optical-fiber • Full duplex • Uses non-return-to-zero encoding • Flow control run by a slack buffer STOP GO Slack Buffer

  8. Myrinet: Packets and Routing • Leading byte determines the outgoing port • MSB of each header byte distinguishes between “host” and “switch” packets • Variable payload length • 8-bit CRC

  9. Myrinet: Switches • Use blocking-cut-through routing • Each contains two custom VLSI chips • crossbar-switch • dual interface • Topology is arbitrary

  10. Myrinet: Host Interface • Available for PCI and Sbus • 32-bit SRAM for MCP • Can act as a slave or a bus master

  11. Myrinet: Software • MCP • Handles all interfacing with the network • Continuously mapping and monitoring the network • Host Software • TCP/IP and UDP/IP • Myrinet API

  12. High Performance Virtual Machine • Windows NT 4.0 cluster built at UCSD and UIUC for the NCSA • 96 dual processor nodes • Used a fat-tree network with 8-port Myrinet switches • Was a 56 GFlops system with: • 45 GB of DRAM • 1.6 MB/s bisection bandwidth • 400 GB of disk storage

  13. HPVM: Testing • Tested on four programs • ZeusMP: astrophysical phenomena in 3D • Cactus: modular 3D numerical relativity • AS-PCG kernel: linear systems solver • QMC kernel: Quantum Monte Carlo simulator • Compared with a Cray T3E and an Origin 2000

  14. HPVM: Results • Performed from 2 to 4 times slower • Slower floating point calculations • Flow control limitations of Myrinet • Much better price/performance ratio

  15. Conclusions • Myrinet is: • Flexible • Fast • Affordable systems with acceptable performance

More Related