** Changed in: linux (Ubuntu)
       Status: Fix Committed => In Progress

** Changed in: linux (Ubuntu)
     Assignee: (unassigned) => dann frazier (dannf)

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  thunder: faulty TSO padding

Status in linux package in Ubuntu:
  In Progress
Status in linux source package in Xenial:
  In Progress

Bug description:
  Certain packet sizes will trigger spurious TCP retransmissions on Cavium 
Thunder-X systems when TSO is enabled (the default). This can result in excess 
traffic and additional latency.

  [Test Case]
  Connect 2 systems to a 10G switch:
   - 1 ThunderX node (the client)
   - 1 "other" node - doesn't have to be ThunderX (the server)
  On the server, run the "receiver" command from the attached tcptest tarball:
    $ ./receiver
  Also on the server, run tcpdump to capture the traffic:
    $ sudo tcpdump -i <iface> -w tcpdump.out
  On the client, run the "sender" command from the tcptest tarball, with a 1461 
packet size:
    $ ./sender <ip of receiver> 1461 1461
  Kill the tcpdump process, and open it in wireshark.

  On failure, you'll see several "[TCP Spurious Retransmission]" packets
  - on success you should see none.

  [Regression Risk]
  Fix is upstream, so regressions will have upstream support. Fix is limited to 
a driver that is only applicable to the Cavium Thunder-X SoC, so risk is 
negligible to other platforms.

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