How to set Linux Max Queue Length ?

Discussion in 'Linux Networking' started by Haifeng Zhu, Nov 6, 2004.

  1. Haifeng Zhu

    Haifeng Zhu Guest

    Hi, folks,

    Do you know how to increase the FIFO (both input and output) packet queue
    limits (Default is 100 packets) to, say, 1000 packets ?

    I mean, where is the file that defines this default limit ?

    Also, this seems to be the protocol independent queue. I want to increase
    all possible internal queues that a packet may pass through a Redhat 9
    Linux that acts as a router. Is there also a network card queue
    ("ifconfig eth0 txqueuelen 1000"? but what is the receiving side "ifconfig
    eth0 rxqueuelen 1000" -- tried, but incorrect).

    -- Haifeng
    Haifeng Zhu, Nov 6, 2004
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  2. Haifeng Zhu

    Alex Harsch Guest

    Hello Haifeng,

    this parameter can not be modified, because there is not limit to this
    Each processor has a softnet_data structure, which holds a list with packets
    received by the NIC. In this structure, the average lenght of the backlog
    queue is stored. Using this number, the congestion level is calculated.
    If the congestion level is too high, the kernel will try to solve the
    problem, for example by turning the device in the polling mode. A device
    won't raise interrupts any more in this mode, so if the processor don't
    poll fast enough, packets will be lost.

    With kind regards, Alex
    Alex Harsch, Nov 7, 2004
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