Lecture: networking

preparation

• finish the IX exercise

overview

• example: Linux
  • receive: NIC queue -> interrupts -> queue to upper layers (e.g., TCP) -> sockets -> apps
  • performance downsides?
  • see more on scalability
• example: high-performance network servers
  • short & a large number of requests
  • througput vs. latency
  • isolation vs. efficiency
  • compatibility & admin
• approaches & trade-offs
  • application/user-level networking stacks
  • new hardware
  • new protocols (e.g., RDMA)
  • new syscall APIs
  • new OS designs (e.g., exokernels)
• IX
  • new API & OS design
  • within Linux through Dune
  • IX kernel: guest kernel mode
  • IX apps & libix: guest user mode
  • main ideas: batching, run to completion, polling, zero copy, multiple NIC queues
  • trade-offs: dedicated resources vs. sharing