Question
KDE Neon power‑saving feature not lowering costs during low‑traffic workload
Cig Cedar
0 reputation · 30 Jul 2025, 04:48 UTC
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0 reputation · 30 Jul 2025, 04:48 UTC
When running a low‑traffic workload on a KDE Neon system, the expected reduction in operational costs from enabling a power‑saving feature is not observed.
The workload consists of occasional HTTP requests with long idle periods. The system is configured to use the built‑in power‑management option that should scale down CPU frequency and suspend unused services during idle times.
What specific checks or configurations should be verified to ensure the power‑saving feature is actually active and contributing to cost reduction for this workload?
34775 reputation · 30 Jul 2025, 12:03 UTC
To ensure the KDE Neon power‑saving feature actually lowers operational costs during a low‑traffic workload, verify the following:
Power‑saving actions in KDE Neon only take effect when the system is truly idle. If PowerDevil is stopped, the On‑AC profile forces full‑speed CPUs, or the hardware lacks ACPI/CPU‑scaling support, the expected cost reduction will not materialise.
kdeneonsystemctl status powerdevil
# If inactive, start it
sudo systemctl start powerdevil
kwriteconfig5 --file powerdevilrc --group PowerProfile --key OnAcProfile
Open System Settings → Power Management → Profiles and confirm CPU Frequency Scaling is set to Power Saver and brightness is lowered. Switch to the Battery profile if you want lower consumption while plugged in.
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
# While the machine is idle, the value should drop below the max.
Repeat the command after a short idle period. If the frequency stays at the maximum, scaling is not applied.
top -b -d 5 | grep Cpu
# Look for idle% approaching 100% during idle periods.
If background services (e.g., systemd timers, network daemons) keep the CPU busy, the power‑saving feature will not be triggered.
Does your CPU and BIOS/UEFI expose ACPI and CPU‑frequency scaling? If not, PowerDevil cannot lower the clock, and no cost reduction will occur.
powertop to confirm actual consumption changes.Use comments to ask for clarification. Post a solution as an answer.
34,775 reputation · 30 Jul 2025, 09:17 UTC
The verification steps above will tell you whether PowerDevil and CPU scaling are working, but there's a second question worth asking: even when everything is configured correctly, how much can it actually save on this workload?
On a low-traffic machine with long idle periods, the CPU is already dropping into deep C-states on its own. The power-saver profile mostly caps frequency and dims the screen — it can't reduce the fixed draw from the PSU, motherboard, RAM, and idle GPU, which dominate consumption at idle. So a correct configuration can still produce a near-zero change on the bill.
Two practical follow-ups:
power-saver and balanced modes during a real idle window, and compare — OS settings alone won't tell you the delta. powerprofilesctl get confirms the active profile, and turbostat shows whether the CPU is already reaching deep C-states.rtcwake or Wake-on-LAN typically saves far more than any CPU tuning — but test that services resume within your acceptable response time before relying on it.Exact figures depend heavily on hardware and PSU efficiency at low load, so treat any wattage estimates as illustrative until measured on your machine.