Thermal Profiles User Guide#

Overview#

Intel® Core™ Ultra edge nodes let you control how the platform reacts as its temperature rises — when fans spin up, when the CPU frequency is capped, and when idle cycles are forced in as a hard limit. The Infrastructure Blueprint ships a local tool under tools/power-tuning/ that configures this policy through the Linux thermal daemon, thermald:

  • Apply a ready-made thermal profile (cool, warm, hot, thermal-max).

  • Set an explicit set of custom trip points (Fan / Processor / powerclamp).

  • Optionally add the CHRG (battery charge) cooling device.

  • Disable thermald to revert to kernel default thermal control.

set_thermal_profile.sh generates, validates, applies and verifies a /etc/thermald/thermal-conf.xml with a staged escalation on the CPU package sensor (x86_pkg_temp):

Fan (active)  <  Processor (passive)  <  intel_powerclamp (passive)
fans on early    cap CPU frequency       inject idle cycles (hard limit)

It then makes thermald the sole thermal authority (a systemd drop-in that runs thermald with --ignore-default-control and without --adaptive, so firmware DPTF/GDDV adaptive tables do not override the trip points).

On the target system: the commands below use repository-relative paths (tools/power-tuning/…), which work when you run them from the repo root. On a host provisioned with Infrastructure Blueprint, the same tools are available on the target system at /opt/edge/developer/tools/power-tuning/. Either cd /opt/edge/developer and use the relative paths as written, or prefix each command with the full path (e.g. sudo /opt/edge/developer/tools/power-tuning/set_thermal_profile.sh --profile warm).

This thermal profile pairs with the power envelope from set_power_profile.sh: the power cap bounds how much heat is produced, while the thermal profile governs how the platform responds as the package temperature climbs. Apply the power envelope first, then the thermal policy.

Note: Unlike the runtime-only RAPL power cap, the thermal config and systemd override are written to disk and persist across a reboot — see What Persists Across a Reboot.

Prerequisites#

  • An Intel x86_64 host (Core Ultra / Panther Lake recommended).

  • thermald installed (it consumes the generated config and drives the cooling devices). Not required for --dry-run or --output mode:

    sudo apt-get install -y thermald

  • sudo access. The script writes to /etc/thermald/, installs a systemd drop-in, and restarts the service. It does not self-elevate, so apply and --disable runs must be invoked with sudo.

  • Cooling devices exposed by the kernel. The script wires in whichever of Fan, Processor, intel_powerclamp (and CHRG when --charge is given) are present, and refuses to write an empty zone if none exist. Check with:

    grep . /sys/class/thermal/cooling_device*/type

Thermal Profiles#

A profile is a set of three trip points on the CPU package sensor, ordered Fan (active) < Processor (passive) < powerclamp (passive). Trip points are in degrees Celsius.

Profile

Fan

Processor

powerclamp

Typical use

cool

55

70

80

Aggressive cooling; fans on early, runs coolest/quietest at the cost of performance

warm (default)

60

75

85

Balanced

hot

70

90

95

Lets the platform run warmer before intervening

thermal-max

95

100

104

Pushes to Tjmax headroom; runs hot

custom

--fan

--proc

--clamp

Supply your own trip points

Terminology#

Term

Meaning

thermald

The Linux thermal daemon that consumes the generated thermal-conf.xml and drives the cooling devices.

trip point

A temperature threshold at which a cooling action is engaged.

active trip

A cooling response that does not cost performance — here, turning fans on.

passive trip

A cooling response that reduces performance to shed heat — frequency capping or idle injection.

x86_pkg_temp

The CPU package temperature sensor the profile escalates on.

Fan

The active cooling device engaged at the first (lowest) trip.

Processor

The passive cooling device that caps CPU frequency at the middle trip.

intel_powerclamp

The passive cooling device that injects idle cycles (hard limit) at the top trip.

CHRG

The battery-charge cooling device; optionally added to the top trip when present (--charge).

Tjmax

The silicon’s maximum junction temperature (~110 °C); the top trip must stay below it (< 105).

DPTF / GDDV

Firmware adaptive thermal framework/tables that would override the config unless thermald runs without --adaptive.

Apply a Named Profile#

Use set_thermal_profile.sh with --profile. The profile must be given via the flag; a bare positional word is rejected. Run from the repository root:

# Balanced (default) — Fan 60 / Processor 75 / powerclamp 85 °C
sudo tools/power-tuning/set_thermal_profile.sh --profile warm

# Aggressive cooling — fans on early, coolest/quietest
sudo tools/power-tuning/set_thermal_profile.sh --profile cool

# Run warmer before intervening
sudo tools/power-tuning/set_thermal_profile.sh --profile hot

# Push to Tjmax headroom — runs hot; warn on fanless/constrained enclosures
sudo tools/power-tuning/set_thermal_profile.sh --profile thermal-max

# Add the battery-charge (CHRG) cooling device to the top trip, if present
sudo tools/power-tuning/set_thermal_profile.sh --profile cool --charge

# Preview only — print the plan and generated XML without changing anything
tools/power-tuning/set_thermal_profile.sh --profile warm --dry-run

Set Custom Trip Points#

For fine-grained control, supply your own three trip points instead of a named profile. All three are required and must satisfy fan < proc < clamp with clamp < 105 (must stay below Tjmax).

# Custom escalation — Fan 50 / Processor 65 / powerclamp 78 °C
sudo tools/power-tuning/set_thermal_profile.sh --profile custom \
  --fan 50 --proc 65 --clamp 78

# Preview a custom profile without applying it
tools/power-tuning/set_thermal_profile.sh --profile custom \
  --fan 50 --proc 65 --clamp 78 --dry-run

Option

Meaning

-p, --profile <name>

Profile to apply: cool, warm, hot, thermal-max, or custom (default warm).

--fan <C>

Fan (active) trip in Celsius (custom only).

--proc <C>

Processor (passive) trip in Celsius (custom only).

--clamp <C>

powerclamp (passive) trip in Celsius (custom only).

--charge

Add the CHRG (battery charge) cooling device to the top trip, if present on this platform.

-o, --output <file>

Write the XML to <file> instead of installing it. Implies no daemon changes.

--disable

Stop thermald and disable it at boot (reverts to kernel default thermal control).

-n, --dry-run

Print the plan and generated XML; write nothing, change nothing.

Generate the XML Without Applying It#

To produce the thermal-conf.xml for review or use elsewhere without touching the running daemon, write it to a file with -o/--output:

sudo tools/power-tuning/set_thermal_profile.sh --profile warm -o /tmp/thermal-conf.xml

This writes only the XML and makes no daemon changes.

Disable Thermald (Revert to Kernel Default)#

To fully revert to kernel default thermal control, disable thermald. This stops the service and disables it at boot, leaving the config and override files untouched:

sudo tools/power-tuning/set_thermal_profile.sh --disable

Re-enable it later with:

sudo systemctl enable --now thermald

Verify and Monitor#

After applying, confirm thermald is active and is the sole thermal authority (the effective ExecStart contains --ignore-default-control and not --adaptive):

systemctl is-active thermald
systemctl show thermald -p ExecStart

To watch the package temperature cross the trip points under load, pair this with the power-tuning monitor and stress tools (see Power Profiles):

# Terminal 1 — live power/thermal monitor (watch PkgTmp against the trips)
cd tools/power-tuning && sudo ./pt_mon.sh

# Terminal 2 — drive the platform hot enough to exercise the trip points
tools/power-tuning/stress_gen.sh --duration 3m

Watch for the escalation stages engaging in order: fans on at the Fan trip, frequency capping at the Processor trip, and idle injection at the powerclamp trip.

Side Effects and Tips#

  • thermal-max runs hot: its top trip sits near Tjmax, so the platform intervenes only very late. On fanless / thermally constrained enclosures this can mean sustained high temperatures — prefer cool or warm there.

  • Fanless platforms: if no Fan cooling device exists, the active step is omitted and the platform relies solely on the passive steps (frequency cap + idle injection).

  • Sole thermal authority: the systemd override runs thermald without --adaptive so firmware DPTF/GDDV adaptive tables cannot override the trip points. If the profile seems ignored, confirm the effective ExecStart still has --ignore-default-control and no --adaptive.

  • Config is validated first: the script parses the generated XML in thermald test-mode before installing it and aborts without changing the system if it does not validate.

  • Brief management gap: applying a profile restarts thermald; if the script aborts mid-run it restores the previously running daemon.

What Persists Across a Reboot#

Unlike the runtime-only RAPL power cap from set_power_profile.sh, the thermal config and systemd override are written to disk and persist across a reboot:

What changes

Where it lives

Reverts on reboot?

Thermal trip points

/etc/thermald/thermal-conf.xml

No — thermald re-reads it at the next boot.

Sole-authority ExecStart

/etc/systemd/system/thermald.service.d/override.conf

No — the drop-in stays on disk.

To change the trip points, simply re-run with a different --profile (the script backs up the previous config to ${CONF_FILE}.bak and the override to ${OVERRIDE_FILE}.bak). To restore the previous config manually:

sudo cp /etc/thermald/thermal-conf.xml.bak /etc/thermald/thermal-conf.xml
sudo systemctl restart thermald

To fully revert to kernel default thermal control, run with --disable (see Disable Thermald).