TSO, SMP and the em driver.

[Jack Vogel]

On 9/12/06, Andre Oppermann <andre at freebsd.org> wrote:
> Ian FREISLICH wrote:
> > 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:
>
> OACTIVE means the interface is stuck.  This looks like a bug in the
> em(4) driver.  I've copied Jack Vogel, the driver maintainer from Intel,
> into this email.
>
> --
> Andre
>
> > 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 at 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.

Hmm, so if memory serves Linux disallows TSO when you are only
at 100Mb, I dont recall why, I will have to look into that and perhaps
have that same limitation in our driver.

Any other data you can give me?

Cheers,

Jack