It has come to my attention that we've never had an accurate report of CPU use on our unix boxes with Zabbix. Windows servers seem to report accurately within variance of the 1 min average. In all versions of the agent from 2.0, 2.2 and 2.4, both Ubuntu and Redhat do not report proper use.

system.cpu.util[,system,avg1]
system.cpu.load[all,avg1]

Both of these have been tried. The first is what has always been used, and works on Windows. Both of these report about the same info on *nix, but they leave out pretty much all the CPU utilization, specifically all apache processes. So while Zabbix says my webservers are using about 3% CPU with these keys, they can actually be up at 85% CPU use, which can be seen both in the "top" command, as well as the charts in vsphere.

It would appear this has always been a major defect and we have never seen actual CPU use from an agent on Ubuntu or Redhat. I can find no other key to monitor CPU use that would give accurate info.