[Bug 234624] FreeBSD 12.0 ix driver TX TSO vlan-tagged network regression from 11.2

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=234624

--- Comment #3 from Nick <freebsd at aoeu.uk> ---
Hi,

One further point of data: ipv6 testing shows the same results as ipv4, both
for tagged and untagged interfaces.

I've also discovered something odd: once TSO has been disabled on an interface,
or if it was disabled at boot, I'm unable to subsequently trigger the issue on
a tagged interface.  Either turning TSO on after boot for some reason doesn't
cause the problem, or my attempts to turn TSO on after boot are failing.  I'm
not really sure how to check for definite, but I do seee that the tsx_tx
counters don't increase from 0 in this case, so I suspect TSO hasn't really
been re-enabled for some reason:

Booted with TSO disabled on ix0:

19:09:27 root at filer:/root/ sysctl dev.ix.0 | grep -i tso
dev.ix.0.queue3.tso_tx: 0
dev.ix.0.queue2.tso_tx: 0
dev.ix.0.queue1.tso_tx: 0
dev.ix.0.queue0.tso_tx: 0

Enable TSO:

19:15:11 root at filer:/root/ ifconfig ix0 tso

TX test shows good behaviour:

19:18:00 root at filer:/root/ iperf3 -c 10.21.10.4
Connecting to host 10.21.10.4, port 5201
[  5] local 10.21.10.2 port 54437 connected to 10.21.10.4 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  1.15 GBytes  9.90 Gbits/sec    0   1.09 MBytes       
[  5]   1.00-2.00   sec  1.15 GBytes  9.88 Gbits/sec    0   1.09 MBytes       
[  5]   2.00-3.00   sec  1.15 GBytes  9.89 Gbits/sec    0   1.09 MBytes       
[  5]   3.00-4.00   sec  1.15 GBytes  9.90 Gbits/sec    0   1.09 MBytes       
[  5]   4.00-5.00   sec  1.15 GBytes  9.90 Gbits/sec    0   1.09 MBytes       
[  5]   5.00-6.00   sec  1.15 GBytes  9.89 Gbits/sec    0   1.09 MBytes       
[  5]   6.00-7.00   sec  1.15 GBytes  9.89 Gbits/sec    0   1.09 MBytes       
[  5]   7.00-8.00   sec  1.15 GBytes  9.88 Gbits/sec    0   1.09 MBytes       
[  5]   8.00-9.00   sec  1.15 GBytes  9.90 Gbits/sec    0   1.09 MBytes       
[  5]   9.00-10.00  sec  1.15 GBytes  9.90 Gbits/sec    0   1.09 MBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  11.5 GBytes  9.89 Gbits/sec    0             sender
[  5]   0.00-10.00  sec  11.5 GBytes  9.89 Gbits/sec                  receiver

Re-check TSO counters, discover they haven't increased:

19:18:11 root at filer:/root/ sysctl dev.ix.0 | grep -i tso
dev.ix.0.queue3.tso_tx: 0
dev.ix.0.queue2.tso_tx: 0
dev.ix.0.queue1.tso_tx: 0
dev.ix.0.queue0.tso_tx: 0

I'm pretty much out of ideas as to how to proceeed with diagnosis at this
point.  I'm happy to perform any further testing you may need, but disabling
TSO seems to adequately solve the problem for me, so I'll just do that.  If you
want to attempt to reproduce, I think our minimal config to reproduce is thus:

FreeBSD 12.0-Release (amd64) running with an X520-DA2 card installed, with one
port in a failover lagg, configured with a vlan-tagged interface on top, with
TSO enabled on ix<whichever> in rc.conf.

In case the platform is relevant, this machine is a Xeon E3-1245v3 (with HT
disabled in BIOS), running on an ASRock C226WS with 4 x DDR3 ECC DIMMs
installed.

Kind regards,

Nick

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