reproductible hang with if_em

From: Pierre Beyssac (beyssac_at_enst.fr)
Date: 09/27/04

  • Next message: Julian Elischer: "Re: FreBSD & MPLS stack" 
    Date: Mon, 27 Sep 2004 20:27:22 +0200
To: freebsd-net@freebsd.org

    Hello,

    I'm having a problem (under 5.3-BETA, but I don't think it matters
    much) with the if_em driver on bursty outbound traffic: the card
    is stuck in a state where it only returns ENOBUFS. No buffers ever
    become available again, but ifconfig down+up fixes the problem.

    >From a quick analysis it looks like the TX descriptor cleanup routine
    em_clean_transmit_interrupts() as called by em_encap() in such cases
    doesn't manage to find anything free with E1000_TXD_STAT_DD set.
    The card seems stuck in this state. A simple albeit dirty fix would
    be to cancel some or all untransmitted packets in such cases.

    Perhaps this is related to my using the card on a 100Mbps switch.
    I have a small program to exercise the hang in case someone would
    like to have a look at it.

    See below for the result of "sysctl hw.em0.debug_info=1" (notice
    the not avail1 = 12 and not avail2 = 0 hinting at
    em_clean_transmit_interrupts).

    em0: [MPSAFE]
    em0: bpf attached
    em0: Ethernet address: 00:0d:56:d0:5c:15
    em0: Speed:N/A Duplex:N/A
    em0: Link is up 100 Mbps Full Duplex
    em0: Adapter hardware address = 0xc3570b34
    em0:tx_int_delay = 66, tx_abs_int_delay = 66
    em0:rx_int_delay = 0, rx_abs_int_delay = 66
    em0: fifo workaround = 0, fifo_reset = 0
    em0: hw tdh = 238, hw tdt = 238
    em0: Num Tx descriptors avail = 256
    em0: Tx Descriptors not avail1 = 12
    em0: Tx Descriptors not avail2 = 0
    em0: Std mbuf failed = 0
    em0: Std mbuf cluster failed = 0
    em0: Driver dropped packets = 0 

    -- 
Pierre Beyssac						pb@enst.fr
_______________________________________________
freebsd-net@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
  • Next message: Julian Elischer: "Re: FreBSD & MPLS stack"

    Relevant Pages