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[Brad Figg <brad.figg@xxxxxxxxxxxxx>]

This bug is missing log files that will aid in diagnosing the problem.
>From a terminal window please run:

apport-collect 1388276

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable
to run this command, please add a comment stating that fact and change
the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the
Ubuntu Kernel Team.

** Changed in: linux (Ubuntu)
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1388276

Title:
  14.10 about 2 to 3 times slower to perform concurrent tasks

Status in “linux” package in Ubuntu:
  Incomplete

Bug description:
  I've just upgraded two servers to use 14.10 (they were before at 14.04) and found that my builds were taking much longer:
  - A jenkins regression test suite that took about 135 minutes is now taking about 300 minutes.
  - A C complation tasks  which took the following amount of time (time from tcsh):
   419.633u 9.471s 1:36.78 443.3%  0+0k 0+166968io 0pf+0w
  is now taking
   519.637u 11.022s 4:42.80 187.6% 0+0k 0+176216io 0pf+0w

  Both tasks are heavily using all the available cores of the processor.
  In one case it is a dual socket E5420 ( 8 cores), in another case it
  is a virtualized 8 cores E5645.

  I first thought it could be the new version of gcc (4.9) since both
  tasks involves a lot of C compilation. Although gcc 4.9 is slower (3s
  vs 2.8s in my own tests) it is not enough to explain the difference. I
  actually also tried using gcc 4.8 and 4.7 with the same performance
  degradation.

  I unfortunately do not have a 14.04 server to which I can compare the
  results to see where the difference is in terms of performance.

  Is anyone observing the same behavior?

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