kernel-packages team mailing list archive

[Timothy Pearson <kb9vqf@xxxxxxxxxxxxxxxxxxxx>]

The machine I originally tested the 4.4 kernel on is not available right
now; I will retry as time permits.  Would the dmesg output from the
failed boot help or are you looking for something else in the apport
output?

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https://bugs.launchpad.net/bugs/1536837

Title:
  Severe performance regression in Infiniband or IPoIB

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  When upgrading to the latest 4.4 test kernel from mainline
  development, all IPoIB links showed a severe performance regression as
  compared with kernel 4.2.  The bandwidth of each link dropped from
  around 3Gbps to around 3Mbps (3 orders of magnitude worse!); reverting
  to the 4.2 kernel immediately fixed this problem.

  The 4.3 kernel from Debian does not appear to suffer from this
  regression.  The regression shows up on both IB ports of the Mellanox
  MT25208 controller.  Other hardware has not been tested.

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