If PRTG (Paessler Router Traffic Grapher) is displaying CPU usage above 100%, it can seem confusing. However, this anomaly often has logical explanations tied to how monitoring tools calculate and display resource utilization.
Reasons for CPU Usage Over 100%
- Multicore Processors:
- PRTG calculates CPU usage by aggregating data from all cores of a processor. For example, a system with 4 cores could theoretically show up to 400% if each core is fully utilized.
- If your system shows over 100%, it’s likely the total usage across all cores rather than a single-core percentage.
- Hyper-Threading:
- Processors with hyper-threading can double the logical cores, further increasing the maximum CPU utilization percentage.
- PRTG includes these logical cores in its calculation, which can inflate the displayed values.
- Monitoring Configuration:
- Misconfigured sensors or overlapping queries can result in duplicated data, leading to artificially high usage readings.
- Background Processes:
- A sudden spike in background processes or high-load applications can push the overall CPU usage beyond expected values, especially on systems with intensive workloads.
Troubleshooting Steps
- Verify Core Calculations:
- Check the number of physical and logical cores on your system.
- Compare the total CPU usage displayed in PRTG with your system’s task manager or performance monitor.
- Review Sensor Settings:
- Inspect the PRTG sensors monitoring CPU usage to ensure there’s no duplication or misconfiguration.
- Update PRTG:
- Ensure you’re using the latest version of PRTG, as older versions may have calculation bugs.
- Analyze Background Load:
- Identify and manage processes consuming high CPU resources to prevent spikes.
Conclusion
Seeing CPU usage above 100% in PRTG is often due to multicore aggregation or logical core calculations rather than an actual system fault. By understanding how PRTG interprets and reports data, you can resolve concerns and optimize monitoring configurations.