Update 2.2 -> 2.3: High CPU Peaks central Site

[Heavy]

@mbunkus

One thing that happened to more than one person (to me, too) is that when you upgrade your agents to 2.3.0 & enable the new way of connecting to the server, you might not have deactivated the agent encryption that was present before 2.3.0 already — ending up with two layers of encryption.

It is not only the double layer of encryption, but also a change in the key derivation function of the symmetric encryption between Checkmk Agent 2.2 and 2.3 that eats up much CPU time. See this forum thread:

Significant CPU Increase After Upgrading to Checkmk 2.3.0p24

Preliminary results seem to indicate that it drops CPU usage by about half (meaning down from 60% total to 30% total), which is incredibly nice to see. Very good catch, & thanks for posting about it.