Public bug reported:
[Impact]
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.
** Affects: linux (Ubuntu)
Importance: High
Status: Fix Committed
** Affects: linux (Ubuntu Xenial)
Importance: High
Assignee: dann frazier (dannf)
Status: In Progress
** Attachment added: "tcptest.tar"
https://bugs.launchpad.net/bugs/1623627/+attachment/4741130/+files/tcptest.tar
** Also affects: linux (Ubuntu Xenial)
Importance: Undecided
Status: New
** Changed in: linux (Ubuntu Xenial)
Status: New => In Progress
** Changed in: linux (Ubuntu Xenial)
Importance: Undecided => High
** Changed in: linux (Ubuntu Xenial)
Assignee: (unassigned) => dann frazier (dannf)
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https://bugs.launchpad.net/bugs/1623627
Title:
thunder: faulty TSO padding
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