Introduction

• Virtual Interface Architecture: http://www.viarch.org, Specification: san_10.pdf
  Intel: http://www.intel.com/design/servers/vi/index.htm
• Intended for high speed, high reliability, low latency, high bandwidth networking
• From An Implementation and Analysis of the Virtual Interface Architecture:
  "U-Net sought explicitly to virtualize the descriptor queue and buffer structure seen by device drivers at user level. It is, of all the ULNs, the most similar to VIA, ... It was the first solid demonstration of fast user level communication over conventional Ethernet and ATM LANs and advanced the state of application-specific protocols."
• Per message overhead, latency high (small messages!)
• Move communication into user space; kernel out of the critical path

Look Ma, no kernel!

• reduce time to wire
• save copy
• can save context switch
• issues: - multiplexing and scheduling, - protection, - resource management, - interface
• gains: - low communication latency, - low communication overhead, - protocol flexibility

U-Net explained

• endpoint creation
• shared buffer
• connection creation
• descriptors
• send, receive, free queues
• doorbells
• ..., multiplexing, kernel emulation, direct access

Implementation and Performance

• SBA-100, SBA-200
• Active messages, Split-C
• TCP, UDP, IP
• reliable fabrics
• VIA

Discussion

• Scalability: connections, nodes
• Restricted to single NIC
• Naming, routing, discovery
• Broadcast?
• Reliablity, QoS