[Xen-users] slow system on Intel J4205 CPU

[matthias <matthias@xxxxxxxx>]

Hi,

I have a problem with xen running very slow on a rather new system:

ASRock J4205-ITX, with an Intel J4205 (Apollo Lake) CPU

The system is running that slow that even the command-line input is
delayed. The problem occurs already in dom0 when no other domains are
running.

Dom0 is a Debian Stretch installation, which runs absolutely fine and
fast if booted without the hypervisor being loaded.

As I was not able to figure things out with the Debian shipped version
of xen (4.8.1), I switch to the most recent one build from source
(RELEASE-4.9.0). This did however not resolve the issue. As the hardware
is rather new I also switched to a more recent kernel 4.11.0 as well
build from source (debian way), which was no help as well.

The two linked log files below are recorded with the system running this
versions: xen 4.9.0 and linux 4.11.0

xl dmesg > hypervisor.log   https://pastebin.com/4sV3MuLn
dmesg > dom0.log            https://pastebin.com/tkgCu6Pa

I have the feeling that the problem might be related to the systems
timers or the power management of the CPU, as I was able to find similar
issues in this thread: https://forums.freebsd.org/threads/59653/
The kernel and the debian installation is however running fine without
the xen hypervisor.

I played around with some of the xen power settings as described in
https://wiki.xen.org/wiki/Xen_power_management or
https://support.citrix.com/article/CTX200390, and was able to get the
system at least that fast that working with the command line is
possible: xenpm set-scaling-governor performance
The performance is however nowhere near where it should be.

Further then that I was not able to track things down. I would
appreciate any help in sorting things out. If any other information
could be of help, please ask I am happy to provide it.

Thanks in advance!
Matthias


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