Create graph for CPU frequency grouped by processors/cores using Grafana, InfluxDB and collectd

This article shows how to make a graph showing a Linux machine’s CPU frequency changes. This plugin gathers CPU Frequency of all the virtual processors aka cores. In general, this module collects simple data for the processors’ frequencies like the Linux command of showing the number in /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq. The purpose of this article is to make a graph showing CPU frequency changes, which may be a hit for CPU load on the system.

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example cpu cores frequency chart

The Linux machine is using collectd to gather CPU frequency statistics and send them to the time series back-end – InfluxDB. Grafana is used to visualize the data stored in the time series back-end InfluxDB and organize the graphs in panels and dashboards. Check out the previous articles on the subject to install and configure such software to collect, store and visualize data – Monitor and analyze with Grafana, influxdb 1.8 and collectd under CentOS Stream 9, Monitor and analyze with Grafana, influxdb 1.8 and collectd under Ubuntu 22.04 LTS and Create graph for Linux CPU usage using Grafana, InfluxDB and collectd
The collectd daemon is used to gather data on the Linux system and to send it to the back-end InfluxDB.

Key knowledge for the cpufreq collectd plugin

  • The collectd plugin cpufreq official page –
  • The CPUFreq plugin options – There are no options for this plugin, at present.
  • to enable the CPUFreq plugin, load the plugin with the load directive in /etc/collectd.conf
    LoadPlugin cpufreq
  • The CPUFreq plugin collects data every 10 seconds.
  • cpufreq_value – a single Gauge value – a metric, which value that can go up and down. It is used to store the current CPU (or core)frequency. So there are multiple gauge values with different tags for the different cores (processors).
    tag key tag value description
    host server hostname The name of the source this measurement was recorded.
    type cpufreq The current frequency of the current processor or the current core.
    instance processors/cores ids The processors (or cores) starting from 0 to N.
  • A Gauge value – a metric, which value that can go up and down. More on the topic – Data sources.

    A GAUGE value is simply stored as-is. This is the right choice for values which may increase as well as decrease, such as temperatures or the amount of memory used, frequencies, etc.

  • To cross-check the value, the user can use the /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq and replacing the * with integer number like 0, 1, 2, etc.
    [root@srv ~]# cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq

    The values are in Hz for the each virtual processor shown in /proc/cpuinfo under a Linux system.

Keep on reading!