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Message #72069
[Bug 1344430] Re: 10-15% iowait on kvm instances on Ubuntu 14.04
** Tags added: ksm-numa-guest-perf
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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
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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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References