[CentOS] EL9 says: pcp-pmie[2870]: Low random number entropy available 15.6%

Fri Mar 3 10:00:47 UTC 2023
Simon Matter <simon.matter at invoca.ch>

Hi,

I've discovered an issue which I don't understand. On a new test install
of EL9 I saw this message in the logs:

Mar 01 08:09:18 <hostname> pcp-pmie[2870]: Low random number entropy
available 15.6%avail at beta.corp.invoca.ch

This is on a 64 core "AMD Opteron(tm) Processor 6282 SE" server but I also
got the same low entropy on an EL9 KVM guest running on a "AMD EPYC 7601"
server.

After a lot of searching the net I understand that rng has been reworked
in 5.x kernels and /proc/sys/kernel/random/entropy_avail reaches only 256
in default configurations. But why does it go too low on a test system
with almost not load?

Is this an issue with AMD CPUs or does it also happen on other systems?

Thanks for any insights,
Simon