kernel-packages team mailing list archive

[Chris J Arges <1344430@xxxxxxxxxxxxxxxxxx>]

I believe I've found the fix for this issue for 3.13.
If you can, please test the kernel posted on comment #1 on this bug:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1346917
Make sure KSM is enabled; and any workarounds for this bug are disabled.

If this fixes the issue for you, you are welcome to mark this bug as a
duplicate of 1346917.

Thanks!

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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
  --- 
  AlsaDevices:
   total 0
   crw-rw---- 1 root audio 116,  1 Jul 21 13:53 seq
   crw-rw---- 1 root audio 116, 33 Jul 21 13:53 timer
  AplayDevices: Error: [Errno 2] No such file or directory
  ApportVersion: 2.14.1-0ubuntu3.2
  Architecture: amd64
  ArecordDevices: Error: [Errno 2] No such file or directory
  AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
  CRDA: Error: [Errno 2] No such file or directory
  DistroRelease: Ubuntu 14.04
  HibernationDevice: RESUME=/dev/mapper/bootdisk-swap_1
  IwConfig: Error: [Errno 2] No such file or directory
  MachineType: Supermicro H8DG6/H8DGi
  Package: linux (not installed)
  PciMultimedia:
   
  ProcEnviron:
   TERM=screen
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcFB: 0 VESA VGA
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.13.0-29-generic root=/dev/mapper/bootdisk-root ro quiet splash rootdelay=120 nomdmonddf nomdmonisw vt.handoff=7
  ProcVersionSignature: Ubuntu 3.13.0-29.53-generic 3.13.11.2
  RelatedPackageVersions:
   linux-restricted-modules-3.13.0-29-generic N/A
   linux-backports-modules-3.13.0-29-generic  N/A
   linux-firmware                             1.127.2
  RfKill: Error: [Errno 2] No such file or directory
  Tags:  trusty
  Uname: Linux 3.13.0-29-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: root
  _MarkForUpload: True
  dmi.bios.date: 11/25/2013
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: 3.5
  dmi.board.asset.tag: To Be Filled By O.E.M.
  dmi.board.name: H8DG6/H8DGi
  dmi.board.vendor: Supermicro
  dmi.board.version: 1.0
  dmi.chassis.asset.tag: To Be Filled By O.E.M.
  dmi.chassis.type: 17
  dmi.chassis.vendor: Supermicro
  dmi.chassis.version: 1234567890
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr3.5:bd11/25/2013:svnSupermicro:pnH8DG6/H8DGi:pvr1234567890:rvnSupermicro:rnH8DG6/H8DGi:rvr1.0:cvnSupermicro:ct17:cvr1234567890:
  dmi.product.name: H8DG6/H8DGi
  dmi.product.version: 1234567890
  dmi.sys.vendor: Supermicro

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