[Bug]: Landing Page, System. on FreeBSD, the CPU frequency shows NaN GHz #1131

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1. rickhull

   added

   bugSomething isn't workingSomething isn't working

   needs triage

   on Jan 1, 2026
2. rickhull commented on Jan 1, 2026

   

   rickhull

   on Jan 1, 2026

   Author

   More actions

   Evidence

   1. CPU Frequency Data is Available via sysctl

   root@gw:~ # sysctl dev.cpu.0.freq
   dev.cpu.0.freq: 880
   
   root@gw:~ # sysctl dev.cpu | grep freq
   dev.cpu.3.freq: 480
   dev.cpu.2.freq: 480
   dev.cpu.1.freq: 480
   dev.cpu.0.freq: 880

   2. Netdata Collector is Running

   The freebsd.plugin is actively collecting CPU frequency data:

   {
       "plugin": "freebsd.plugin",
       "module": "dev.cpu.0.freq"
   }

   3. Time-Series Chart Works Correctly

   The chart cpu.scaling_cur_freq exists and contains valid data:

   "cpu.scaling_cur_freq": {
       "id": "cpu.scaling_cur_freq",
       "name": "cpu.scaling_cur_freq",
       "type": "cpu",
       "family": "cpufreq",
       "context": "cpu.scaling_cur_freq",
       "title": "Current CPU Scaling Frequency (cpu.scaling_cur_freq)",
       "priority": 1002,
       "plugin": "freebsd.plugin",
       "module": "dev.cpu.0.freq",
       "units": "MHz",
       "dimensions": {
           "frequency": {
               "name": "frequency"
           }
       }
   }

   This chart displays correctly and shows valid frequency values when accessed via /api/v1/data?chart=cpu.scaling_cur_freq.

   4. Metadata API Returns "unknown"

   The /api/v1/info endpoint (used by the landing page) shows:

   {
       "cpu_freq": "unknown",
       "host_labels": {
           "_system_cpu_freq": "unknown"
       }
   }

   The landing page attempts to render the string "unknown" as a numeric value, resulting in "NaN GHz".

   Root Cause Analysis

   The FreeBSD plugin has two separate code paths:

   1. Time-series data collection (working): Reads dev.cpu.0.freq sysctl and creates charts ✅
   2. Metadata population (broken): Should populate cpu_freq field in host info but returns "unknown" ❌

   The metadata field is never populated with the actual CPU frequency value, despite being successfully collected for charting purposes.

   Steps to Reproduce

   1. Install netdata v2.6.3 on FreeBSD 15.0-RELEASE
   2. Ensure dev.cpu.0.freq sysctl exists and returns valid data
   3. Navigate to netdata landing page (port 19999 or via reverse proxy)
   4. Click "System" tab at bottom of landing page
   5. Observe "CPU Frequency" field displays "NaN GHz"
   6. Verify chart works: access /api/v1/data?chart=cpu.scaling_cur_freq shows valid data

   Expected Fix

   The freebsd.plugin should populate the cpu_freq metadata field in /api/v1/info with the current CPU frequency value (e.g., "880" or "0.88" depending on expected format) when it successfully collects this data for charting.

   Workaround

   None. The issue is cosmetic - all charts function correctly. Users can ignore the "NaN GHz" display on the landing page.

   Additional Notes

   • This may affect other FreeBSD systems where dev.cpu.N.freq sysctl exists
   • The related dev.cpu.temperature sysctl genuinely doesn't exist on this hardware (expected)
   • System has 4 CPU cores, all reporting valid frequency data via sysctl
3. ktsaou

   added a commit that references this issue on Jan 28, 2026

   fix(freebsd): CPU frequency detection returns "unknown" causing NaN d…

   ...

   c16b526
4. ktsaou commented on Jan 28, 2026

   

   ktsaou

   on Jan 28, 2026

   Member

   More actions

   Sorry for the delay.
   Fixed in netdata/netdata#21658
5. ilyam8

   closed this as completedin netdata#21658on Jan 28, 2026