** Changed in: linux (Ubuntu)
       Status: In Progress => Fix Released

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  IPv6 with LVS Performance issue in latest 3.13LTS kernels

Status in linux package in Ubuntu:
  Fix Released
Status in linux source package in Trusty:
  Fix Released

Bug description:
  We experienced a major performance regression between 12.04's 3.2 kernels
  and 14.04's 3.13 kernels when using IPv6 with the LVS load-balancing
  facility.  Through analysis of perf events and a workaround we've
  determined that an upstream fix is available which addresses the issue.
  Ubuntu has picked up the "IPv6: remove rt6i_genid" fix that appears to
  address our issue in their 3.16 and later kernels.  This was checked
  into the upstream 3.16 kernel back in late 2014.  This fix addressed an
  issue introduced by the (late 2012) "ipv6: use net->rt_genid to check dst
  validity", which is the source of our issue due to the mismatch between
  a dst/route instantiation's rt6i_genid and the IPv6 rt_genid field.

  Since we have drivers and other software tied to the 3.13 kernels in
  the field this report is requesting that the backport of that upstream
  fix be done to the 3.13 LTS kernels as well since we were planning on
  several more years for those deployed systems.  It seems relatively

  In our 3.13 kernel we used the "systemtap" facility in a test system
  to temporarily address the "obsolete" determination mistakenly made by
  the ip6_dst_check() function to check dst validity on behalf of the LVS
  (ip_vs) code.  By updating rt6i_genid to the current global value we were
  able to restore our test systems to the previous performance obtained
  with the 3.2 kernels.  But clearly we want the official upstream fix
  incorporated, which pulls the troublesome rt6i_genid field out altogether
  since its mishandling affected more than IPv6/LVS support based on the
  upstream mail threads.  Those were made in mid-2014 to the upstream
  kernel folks, such as a per-socket route caching issue.

  Note that the apport-bug collected info from a 3.13.0-87 system but we see the
  issue on all 3.13.0-xxx kernels.

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: linux-image-3.13.0-87-generic 3.13.0-87.133
  ProcVersionSignature: Ubuntu 3.13.0-87.133-generic 3.13.11-ckt39
  Uname: Linux 3.13.0-87-generic x86_64
  ApportVersion: 2.14.1-0ubuntu3.21
  Architecture: amd64
   /dev/snd/controlC0:  marc       2433 F.... pulseaudio
  Date: Mon Aug 29 20:05:57 2016
  HibernationDevice: RESUME=UUID=c4187d86-ea40-4f53-af39-1b7e83964502
  InstallationDate: Installed on 2014-04-30 (852 days ago)
  InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
   Bus 001 Device 003: ID 0e0f:0002 VMware, Inc. Virtual USB Hub
   Bus 001 Device 002: ID 0e0f:0003 VMware, Inc. Virtual Mouse
   Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
  MachineType: VMware, Inc. VMware Virtual Platform
   PATH=(custom, no user)
  ProcFB: 0 svgadrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-87-generic 
root=UUID=92211e82-1c0b-42e6-bb12-0003b7f6db54 ro quiet splash 
   Error: command ['pacmd', 'list'] failed with exit code 1: Home directory not 
accessible: Permission denied
   No PulseAudio daemon running, or not running as session daemon.
   linux-restricted-modules-3.13.0-87-generic N/A
   linux-backports-modules-3.13.0-87-generic  N/A
   linux-firmware                             1.127.22
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 05/20/2014
  dmi.bios.vendor: Phoenix Technologies LTD
  dmi.bios.version: 6.00
  dmi.board.name: 440BX Desktop Reference Platform
  dmi.board.vendor: Intel Corporation
  dmi.board.version: None
  dmi.chassis.asset.tag: No Asset Tag
  dmi.chassis.type: 1
  dmi.chassis.vendor: No Enclosure
  dmi.chassis.version: N/A
  dmi.product.name: VMware Virtual Platform
  dmi.product.version: None
  dmi.sys.vendor: VMware, Inc.

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