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[William Van Hevelingen <1344430@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

After upgrading from Ubuntu 12.04 to Ubuntu 14.04 we began seeing 10-15%
iowait on kvm guests.  The guests had little to no load and yet the
shell was laggy and commands took forever to respond (assuming you could
even type them)

# uname -a
Linux kvm-andromeda 3.13.0-29-generic #53-Ubuntu SMP Wed Jun 4 21:00:20 UTC
2014 x86_64 x86_64 x86_64 GNU/Linux

# kvm --version
QEMU emulator version 2.0.0 (Debian 2.0.0+dfsg-2ubuntu1.1), Copyright (c)
2003-2008 Fabrice Bellard

I posted to Ubuntu Server and they suggested that I upgrade my kernel
version.

Relevant Mailing List discussion:

https://lists.ubuntu.com/archives/ubuntu-server/2014-July/006925.html

After installing a 3.14 kernel the performance returned to normal.

kvm-andromeda:~# uname -a
Linux kvm-andromeda 3.14.1-031401-generic #201404141220 SMP Mon Apr 14 16:21:48 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1344430

Title:
  10-15% iowait on kvm instances on Ubuntu 14.04

Status in “linux” package in Ubuntu:
  New

Bug description:
  After upgrading from Ubuntu 12.04 to Ubuntu 14.04 we began seeing
  10-15% iowait on kvm guests.  The guests had little to no load and yet
  the shell was laggy and commands took forever to respond (assuming you
  could even type them)

  # uname -a
  Linux kvm-andromeda 3.13.0-29-generic #53-Ubuntu SMP Wed Jun 4 21:00:20 UTC
  2014 x86_64 x86_64 x86_64 GNU/Linux

  # kvm --version
  QEMU emulator version 2.0.0 (Debian 2.0.0+dfsg-2ubuntu1.1), Copyright (c)
  2003-2008 Fabrice Bellard

  I posted to Ubuntu Server and they suggested that I upgrade my kernel
  version.

  Relevant Mailing List discussion:

  https://lists.ubuntu.com/archives/ubuntu-server/2014-July/006925.html

  After installing a 3.14 kernel the performance returned to normal.

  kvm-andromeda:~# uname -a
  Linux kvm-andromeda 3.14.1-031401-generic #201404141220 SMP Mon Apr 14 16:21:48 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

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