I had a message saying “ Long-term load (15min avg) larger than number of processors: 4.8 > 4
This may slow down DNS resolution and can cause bottlenecks.”
pi@ph5b:~ $ man proc
[..]
/proc/loadavg
The first three fields in this file are load average figures
giving the number of jobs in the run queue (state R) or waiting
for disk I/O (state D) averaged over 1, 5, and 15 minutes. They
are the same as the load average numbers given by uptime(1) and
other programs. The fourth field consists of two numbers sepa‐
rated by a slash (/). The first of these is the number of cur‐
rently runnable kernel scheduling entities (processes, threads).
The value after the slash is the number of kernel scheduling en‐
tities that currently exist on the system. The fifth field is
the PID of the process that was most recently created on the
system.
Load averages are healthy if its below one for a one CPU system, or below two for a two CPU system, or four for a four CPU system etc.
The longest load average value displayed is over a period of 15 minutes (see man page).
If want to keep track of system load over time, you would need some monitoring like for example Zabbix or Nagios.