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
     
    Joe, Aug 4, 2006
    #1
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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
    #2
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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
    #3
  4. Unsure about latency? However, the fastest nics are usually those
    with intel chipset using e100/e1000 module.
     
    Michael Heiming, Aug 4, 2006
    #4
  5. Joe

    Phil Hobbs Guest

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

    Cheers,

    Phil Hobbs
     
    Phil Hobbs, Aug 4, 2006
    #5
  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:

    ftp://ftp.cup.hp.com/dist/networking/briefs/nic_latency_vs_tput.txt

    hth,

    rick jones
     
    Rick Jones, Aug 4, 2006
    #6
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