Lowest Latency NIC for linux

Discussion in 'Linux Networking' started by Joe, Aug 4, 2006.

  1. Joe

    Joe Guest

    I have a need to develop a system that requires the lowest possible
    latency from the NIC for (typically) a lot of very small packets at
    100Mbit speeds. Can anyone suggest which of the NICs supported by linux
    has the lowest latency? Which has the best support for h/w assistance
    for things like checksumming? Can anyone suggest a good resource for
    this kind of information?

    Many thanks,

    Joe, Aug 4, 2006
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  2. Joe

    iRobx Guest

    You want a NIC with TOE - TCP Offload Engine. A quick google search
    shows that the Hewlett Packard NC370T (374191B22) Network Adapter
    supports Linux and there are probably others as well.
    iRobx, Aug 4, 2006
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  3. Joe

    Joe Guest

    TOE would cover h/w assistance, lowering my CPU overhead, but does it
    (or TSO) improve latency in any way? I've also read bad things about
    TOE and linux... In addition I'm would prefer a "one chip" solution, as
    it is going on a board designed in house for an embedded system.
    Joe, Aug 4, 2006
  4. Unsure about latency? However, the fastest nics are usually those
    with intel chipset using e100/e1000 module.
    Michael Heiming, Aug 4, 2006
  5. Joe

    Phil Hobbs Guest

    Small-packet latency is horrible with TCP/IP over Ethernet. Myrinet is
    much, much better, though much more expensive.


    Phil Hobbs
    Phil Hobbs, Aug 4, 2006
  6. Joe

    Rick Jones Guest

    If the packets are "very small" then CKO doesn't really buy much. If
    the packets are "very small" then the stack processing time is a
    non-trivial chunk of the latency (on an unloaded network at
    least). That suggests you want a NIC driven by the "leanest" driver
    out there.

    To achieve lowest latency with a NIC you typically have to disable the
    interrupt coalescing settings:



    rick jones
    Rick Jones, Aug 4, 2006
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