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[Mohammed Naser <1435363@xxxxxxxxxxxxxxxxxx>]

Hi Chris,

Thanks for the help so far.  I'm deploying a new machine right now and
I'll be trying to replicate it on -48.

The way I detected it was that i'd see messaging in "dmesg" on guest
similar to this:

hrtimer: interrupt took 4352551231 ns

In addition, when pinging the machine,  you'd have a few seconds of
stable pings, then unresponsive for 2-3s, and it starts responding again
(with a huge delay, latency of 3s to 4s because of the delay).

I will be running this machine and monitoring it closely and report on
the output, however, I'd like to note that these machines have heavy KSM
usage, before turning it off, one had almost ~45-50GB of deduplicated
memory on a 256GB node, so I'm not sure if that plays in as a factor..

I'll report back on -48 and see what I can check

Thank you,
Mohammed

-- 
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1435363

Title:
  KSM causing performance and instability issues

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  This seems to be a bug that has regressed, I have encountered the same
  issue as 2 other reports:

  LP: #1346917
  LP: #1349897

  Running kernel: 3.13.0-46-generic

  This is replicated over many compute nodes (KVM) running OpenStack.
  The workaround is to disable KSM:

  echo 2 > /sys/kernel/mm/ksm/run

  This fixes the issue temporarily.
  ---
  AlsaDevices:
   total 0
   crw-rw---- 1 root audio 116,  1 Mar 22 14:30 seq
   crw-rw---- 1 root audio 116, 33 Mar 22 14:30 timer
  AplayDevices: Error: [Errno 2] No such file or directory
  ApportVersion: 2.14.1-0ubuntu3.7
  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
  InstallationDate: Installed on 2014-12-14 (99 days ago)
  InstallationMedia: Ubuntu-Server 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.3)
  MachineType: Dell Inc. PowerEdge R620
  Package: linux (not installed)
  PciMultimedia:

  ProcFB: 0 EFI VGA
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-46-generic.efi.signed root=UUID=68d30a86-3c67-4691-b142-d27a459986e8 ro
  ProcVersionSignature: Ubuntu 3.13.0-46.79-generic 3.13.11-ckt15
  RelatedPackageVersions:
   linux-restricted-modules-3.13.0-46-generic N/A
   linux-backports-modules-3.13.0-46-generic  N/A
   linux-firmware                             1.127.11
  RfKill: Error: [Errno 2] No such file or directory
  Tags:  trusty
  Uname: Linux 3.13.0-46-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups:

  _MarkForUpload: True
  dmi.bios.date: 01/16/2014
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: 2.2.2
  dmi.board.name: 01W23F
  dmi.board.vendor: Dell Inc.
  dmi.board.version: A05
  dmi.chassis.type: 23
  dmi.chassis.vendor: Dell Inc.
  dmi.modalias: dmi:bvnDellInc.:bvr2.2.2:bd01/16/2014:svnDellInc.:pnPowerEdgeR620:pvr:rvnDellInc.:rn01W23F:rvrA05:cvnDellInc.:ct23:cvr:
  dmi.product.name: PowerEdge R620
  dmi.sys.vendor: Dell Inc.

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