On 2018-04-16 23:00, Claudio Jeker wrote:
On Mon, Apr 16, 2018 at 11:10:46PM +0300, Kapetanakis Giannis wrote:
On 16/04/18 18:40, Claudio Jeker wrote:
>
>>really depends on the KVM/linux version
>>
>Don't forget to set "options kvm-intel preemption_timer=0" for modprobe on
>newer linux kernels. After that it seems to work nicely.
>
This module option (according to lists) is about timing issues with
kvm and
obsd.
Does it affect performance as well?
It affects stability (sometimes VM hang because the clock interrupts
don't
work correctly) which is a big performace killer. Also for me stat
clock
was not running so there was no way to know what CPU load the VM has.
which kernel?
I see it for sure on a 4.14 kernel. Guess more affected.
For me the kernels:
Host: 3.2.0-4-amd64 Debian Wheezy 7.11 (and no I don't want to upgrade
this, it's running production vms over 300 days).
Modules:
kvm_intel 122046 78
kvm 291951 1 kvm_intel
I don't use any kvm module options on the Linux host. My host also runs
bunch of other VMs (linuxes with different kernels, freeBSD, windows 7).
Guest: OpenBSD 6.2 default
Searching the module option you have recommended, I have run across this
thread:
http://openbsd-archive.7691.n7.nabble.com/Degraded-timing-performance-QEMU-KVM-OpenBSD-6-2-td333611.html
I have done the "while date loop" test on both my old 6.2 and new 6.3
OpenBSD vm for 30 minutes and I don't experience any slowdowns so this
issue might not affect me but there the OP was using Fedora which is a
complex hodgepodge distro compared to Debian.
