ale(4): Problems with tso, rxcsum and/or txcsum

[Ulrich Spörlein]

On Mon, 15.06.2009 at 21:51:54 +0900, Pyun YongHyeon wrote:
> On Mon, Jun 15, 2009 at 02:16:23PM +0200, Ulrich Sp??rlein wrote:
> > Hello Pyun,
> > 
> > I have connection problems with the onboard GigE of an Asus P5Q board, using a recent 8-CURRENT
> > 
> > ale0: <Atheros AR8121/AR8113/AR8114 PCIe Ethernet> port 0xdc00-0xdc7f mem 0xfe9c0000-0xfe9fffff irq 17 at device 0.0 on pci2
> > ale0: 960 Tx FIFO, 1024 Rx FIFO
> > ale0: Using 1 MSI messages.
> > ale0: 4GB boundary crossed, switching to 32bit DMA addressing mode.
> > miibus0: <MII bus> on ale0
> > ale0: Ethernet address: 00:24:8c:36:3e:10
> > ale0: [FILTER]
> > ale0: link state changed to UP
> > 
> > ale0 at pci0:2:0:0:        class=0x020000 card=0x82261043 chip=0x10261969 rev=0xb0 hdr=0x00
> >     vendor     = 'Attansic (Now owned by Atheros)'
> >     device     = 'PCI-E ETHERNET CONTROLLER  (AR8121/AR8113 )'
> >     class      = network
> >     subclass   = ethernet
> > 
> > ale0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
> >         options=311b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,TSO4,WOL_MCAST,WOL_MAGIC>
> >         ether 00:24:8c:36:3e:10
> >         inet 192.168.0.146 netmask 0xffffff00 broadcast 192.168.0.255
> >         media: Ethernet autoselect (100baseTX <full-duplex>)
> >         status: active
> > 
> > 
> > When transferring data to the machine at ~10MB/s (100Mbit network only) the ssh
> > connection will die after a couple of minutes with
> > 
> > Disconnecting: Bad packet length 1592360521.
> > 
> > After disabling tso, txcsum and rxcsum the connection seems to be
> > stable, though. I fail to figure out a pattern, though. Do I need to
> 
> Hmm, I think this is the second report that could be related with
> Rx checksum offloading. If disabling Rx checksum fix the issue, I
> have to disable it by default until I understand what's going on.

I really need to disable tso, rxcsum *and* txcsum to make this card work
stable. :/

There is one other weirdness, though, regarding tso. I have been using a
netcat-blast test, where I "upload" /dev/zero to another machine, and
"download" it from the same machine.

When tso is enabled, upload is seriously impacted, download is fine
though, observe systat output:

           ale0  in     10.805 MB/s         11.101 MB/s            7.739 GB
                 out     2.574 MB/s          8.740 MB/s            5.891 GB

When disabling tso, while that test is running, it will immediately become this:

           ale0  in      7.498 MB/s         11.101 MB/s            8.270 GB
                 out     7.560 MB/s          8.740 MB/s            6.209 GB  

Which looks more normal. Re-activating tso now has no further consequences to
the stream (it only works for new TCP sessions, right?)


Cheers,
Ulrich Spörlein
-- 
http://www.dubistterrorist.de/