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From: Ian FREISLICH <if@hetzner.co.za>
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Date: Tue, 12 Sep 2006 12:11:52 +0200
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Subject: TSO, SMP and the em driver.
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Hi

I've noticed that after an apparently random period of time something
goes wierd with my networking.  A tcpdump shows traffic is recieved,
but trussing a daemon (sshd for instance) shows the packets are not
making it that far.  Also, no packets are transmitted either.

Here's an ifconfig of the interface while it doesn't transmit or
recieve packets, note the OACTIVE:

em0: flags=8c43<UP,BROADCAST,RUNNING,OACTIVE,SIMPLEX,MULTICAST> mtu 1500
        options=3cb<RXCSUM,TXCSUM,VLAN_MTU,POLLING,VLAN_HWCSUM,TSO4,TSO6>
        inet 41.204.193.40 netmask 0xfffffff0 broadcast 41.204.193.47
        ether 00:04:23:d4:12:2e
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active

If I disable and re-enable TSO, the interface cames back, but
probably because of an interface reset.  It comes back without the
OACTIVE flag and then all works well for some time.

Here's the pciconf output for the ethernet device.

em0@pci3:4:0:   class=0x020000 card=0x10798086 chip=0x10798086 rev=0x03 hdr=0x00
    vendor   = 'Intel Corporation'
    device   = '82546EB Dual Port Gigabit Ethernet Controller'
    class    = network
    subclass = ethernet

So far, it hasn't happened again with TSO disabled over a period
where it happened twice.  Let me know if there's any debugging I
can do for you.  Interestingly, I have 4 more of these dual NICs
running on the same version of the source without ony problems, but
the working cards are on UP machines.

Ian

--
Ian Freislich