9.2 ixgbe tx queue hang

[Christopher Forgeron]

Update:

 I'm changing my mind, and I believe Rick's TSO patch is fixing things
(sorry). In looking at my notes, it's possible I had lagg on for those
tests.  lagg does seem to negate the TSO patch in my case.

kernel.10stable_basicTSO_65535/

- IP_MAXPACKET = 65535;
- manually forced (no if statement) ifp->if_hw_tsomax = IP_MAXPACKET -
(ETHER_HDR_LEN + ETHER_VLAN_ENCAP_LEN);
- Verified on boot via printf that ifp->if_hw_tsomax = 65517
- Boot in a NON LAGG environment.  ix0 only.

ixgbe's printf is showing packets up to 65530. Haven't run long enough yet
to see if anything will go over 65535

I have this tcpdump running to check packet size.
tcpdump -ennvvXS -i ix0 greater 65518

I do expect to get packets over 65518, but I was just curious to see if any
of them would go over 65535. Time will tell.

In a separate test, If I enable lagg, we have LOTS of oversized packet
problems. It looks like tsomax is definitely not making it through in
if_lagg.c - Any recommendations there? I will eventually need lagg, as I'm
sure will others.

With dtrace, it's showing t_tsomax >= 65518. Shouldn't that not be
happening?


dtrace -n 'fbt::tcp_output:entry / args[0]->t_tsomax != 0 &&
args[0]->t_tsomax >= 65518 / { printf("unexpected tp->t_tsomax: %i\n",
args[0]->t_tsomax); stack(); }'


  6  31403                 tcp_output:entry unexpected tp->t_tsomax: 65535

              kernel`tcp_do_segment+0x2c99
              kernel`tcp_input+0x11a2
              kernel`ip_input+0xa2
              kernel`netisr_dispatch_src+0x5e
              kernel`ether_demux+0x12a
              kernel`ether_nh_input+0x35f
              kernel`netisr_dispatch_src+0x5e
              kernel`bce_intr+0x765
              kernel`intr_event_execute_handlers+0xab
              kernel`ithread_loop+0x96
              kernel`fork_exit+0x9a
              kernel`0xffffffff80c75b2e

  3  31403                 tcp_output:entry unexpected tp->t_tsomax: 65535

              kernel`tcp_do_segment+0x2c99
              kernel`tcp_input+0x11a2
              kernel`ip_input+0xa2
              kernel`netisr_dispatch_src+0x5e
              kernel`ether_demux+0x12a
              kernel`ether_nh_input+0x35f
              kernel`netisr_dispatch_src+0x5e
              kernel`bce_intr+0x765
              kernel`intr_event_execute_handlers+0xab
              kernel`ithread_loop+0x96
              kernel`fork_exit+0x9a
              kernel`0xffffffff80c75b2e

  6  31403                 tcp_output:entry unexpected tp->t_tsomax: 65535

              kernel`tcp_do_segment+0x2c99
              kernel`tcp_input+0x11a2
              kernel`ip_input+0xa2
              kernel`netisr_dispatch_src+0x5e
              kernel`ether_demux+0x12a
              kernel`ether_nh_input+0x35f
              kernel`netisr_dispatch_src+0x5e
              kernel`bce_intr+0x765
              kernel`intr_event_execute_handlers+0xab
              kernel`ithread_loop+0x96
              kernel`fork_exit+0x9a
              kernel`0xffffffff80c75b2e

  1  31403                 tcp_output:entry unexpected tp->t_tsomax: 65535

              kernel`tcp_do_segment+0x2c99
              kernel`tcp_input+0x11a2
              kernel`ip_input+0xa2
              kernel`netisr_dispatch_src+0x5e
              kernel`ether_demux+0x12a
              kernel`ether_nh_input+0x35f
              kernel`netisr_dispatch_src+0x5e
              kernel`bce_intr+0x765
              kernel`intr_event_execute_handlers+0xab
              kernel`ithread_loop+0x96
              kernel`fork_exit+0x9a
              kernel`0xffffffff80c75b2e