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Date: Mon, 17 Jun 2002 19:07:59 -0400 (EDT)
From: Gopinath KN <gopi@research.bell-labs.com>
To: <freebsd-net@freebsd.org>
Subject: ti0 Gigabit driver
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Hello All,


    I am noticing that a FreeBSD router is dropping many packets
    in the ip_output() routine (when called from ip_forward()).
    It was confirmed by "packets not forwardable/packets dropped
    due to lack of mbufs etc." messages of "netstat -s -p ip".
    The correponding output interface is the Netgear Gigabit (ti0).

    The giagbit driver sets the interface queue (if_snd of the ifnet
    structure) to a value which is 512 (The TX ring count of the NIC).
    This queue is where the packets are being dropped from.

    Can I increase this value to a larger number (say, 1024)?

    I am not sure what side-effect this is going to have as this
    might involve playing with some device memory. Does the
    NIC hardware/software assume that this value should not be
    beyond the maximum TX ring size (512) as indicated in
    one of the headers?


    Otherwise, can you suggest anyways of reducing/eliminating
    these drops - the CPU is not saturated - it is atleast 20% idle.

               Thanks,
	       Gopi

PS: Kindly  CC replies to me.






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