Linode CPU usage graphs vs Zabbix
The linode graph reports around 50% utilisation at our peak web load, and a brief spike of 240% when I ran some dirty benchmarks. Our graphs show 28% at the same time as the linode manager shows 50%, and 380% when the linode manager shows 240%.
I've gone through the Zabbix source code and determined that it uses /proc/stat for analysing CPU utilisation. I performed the same calculations it does in a quick script and found that the numbers I was getting were consistent with the numbers filtering through Zabbix.
The Linode Support team informed me the Linode Manager graphs are "5 minute averages based on 4 cores, so [we] may be running into discrepancies caused by averages versus discrete values, or scaling depending on how Zabbix handles multiple cores."
I'm waiting on some per-core data from Zabbix, which probably won't start filtering through for a few more hours. Beyond that I'm pretty well stumped.
Does anyone have any ideas? Cheers.
