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[Bug 1344430] Re: 10-15% iowait on kvm instances on Ubuntu 14.04

 

I can boot into the old kernel and run apport-collect if you need that
as well.

** Tags added: apport-collected

** Description changed:

  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
+ --- 
+ ApportVersion: 2.14.1-0ubuntu3.2
+ Architecture: amd64
+ DistroRelease: Ubuntu 14.04
+ Package: linux (not installed)
+ ProcEnviron:
+  TERM=screen
+  PATH=(custom, no user)
+  XDG_RUNTIME_DIR=<set>
+  LANG=en_US.UTF-8
+  SHELL=/bin/bash
+ Tags:  trusty
+ Uname: Linux 3.14.1-031401-generic x86_64
+ UnreportableReason: The running kernel is not an Ubuntu kernel
+ UpgradeStatus: No upgrade log present (probably fresh install)
+ UserGroups: root
+ _MarkForUpload: True

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

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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:
  Confirmed

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
  --- 
  ApportVersion: 2.14.1-0ubuntu3.2
  Architecture: amd64
  DistroRelease: Ubuntu 14.04
  Package: linux (not installed)
  ProcEnviron:
   TERM=screen
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  Tags:  trusty
  Uname: Linux 3.14.1-031401-generic x86_64
  UnreportableReason: The running kernel is not an Ubuntu kernel
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: root
  _MarkForUpload: True

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