SNS - high OS overhead

• Price for many network connections

  • O(n) select loop (hidden by thread scheduler)
  • high network stack overhead (AM, xKernel, …)
    • 10 ?sec in-kernel AM trap, 100 ?sec cross-kernel AM read, 3 msec TCP cross-kernel read()

• Thread subsystem overhead

  • thread context switch 20-50x procedure call
  • RISC: large register sets assume procedure calls more frequent than context switches
  • TranSend: 25-50 kB per-thread state

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