Performance degradation in 4.15 and above

[Gabor Hudiczius <ghudiczius@xxxxxxxxx>]

Hi,

I have an old Proliant DL380 server running Gentoo Linux as Dom0 on Xen 
with several DomUs also running Gentoo Linux. After upgrading to 4.15 I 
have noticed that in some of the DomUs (that are used as Kubernetes 
nodes) the load slowly keeps climbing until it reaches a level that the 
DomU becomes unresponsive and needs to be restarted. This issue is not 
present when running on Xen 4.14 and went away once I downgraded bask to 
4.14. The same issue presented itself again after upgrading to 4.16.
According to some Munin graphs the load increases by 2-4 per day, but as 
far as I can tell nothing else really changes (CPU usage, number of 
processes - ) so I don't really have an idea what is causing the issue.
Both the Dom0 and DomUs are running on a hardened-gentoo kernel version 
5.10.156 (see the attached .config).
If anyone has any pointers regarding where to look or what can be 
tweaked, I would be grateful for the information.
Regards,
Gabor

Attachment: .config
Description: Text document