Set Power Profile

Terminology

Acronyms and terms used throughout this skill.

BIOS Settings (Mandatory)

These platform firmware (BIOS) settings are required for the power tuning in this skill to work. The Intel Low Power Mode daemon (intel_lpmd) needs the OS to own the CPU's power/frequency controls; the settings below hand that control to the OS. Verify them before running the skill — if they are wrong, the script may run without error yet the limits or EPP/EPB tuning will not take effect.

Settings are grouped by their BIOS menu category. The exact names and menu paths vary by vendor; the tables below list common names and the required values. Within each category the Value column states what each setting must be set to.

Advanced → Power & Performance → CPU – Power Management Control

BIOS Settings (Optional)

Not strictly required, but recommended — these improve idle power savings and make sure the OS/intel_lpmd (not firmware) drives frequency and EPP. Please disregard any configurations that are unavailable in your BIOS.

Advanced → Power & Performance → CPU – Power Management Control

How to Use This in Your Workloads

Pick the profile whose PkgWatt budget matches what your workload needs — trading battery life, heat, and fan noise against sustained speed. PkgWatt (the CPU package power) is the profile parameter because it can be enforced on every platform; on silicon that also exposes a psys (SysWatt) domain an extra whole-platform cap is added automatically. Each profile ships a sensible default burst ratio; override it only if you need more or less burst headroom.

• Profile (PkgWatt budget) — from LowPower (10 W) for the coolest, quietest, longest-battery operation up to MaxPerformance (the platform maximum, cTDP Level 2) for the most speed.
• burst_ratio (short bursts) — extra headroom for brief spikes so the system stays responsive without raising the sustained budget.

Pick a profile for your workload

Example commands

# List the available profiles and their PkgWatt budgets
tools/power-tuning/set_power_profile.sh --list

# Longest battery / coolest, silent operation
sudo tools/power-tuning/set_power_profile.sh --profile LowPower

# Balanced interactive use
sudo tools/power-tuning/set_power_profile.sh --profile BalancedHigh

# Max sustained throughput (AI inference / transcode / builds)
sudo tools/power-tuning/set_power_profile.sh --profile MaxPerformance

# Override the default burst ratio for a snappier feel
sudo tools/power-tuning/set_power_profile.sh --profile Performance --burstRatio 1.4

# Profile PkgWatt with an explicit SysWatt cap (psys-capable platforms)
sudo tools/power-tuning/set_power_profile.sh --profile Performance --sysWatt 35

# Preview only — see the plan without changing anything
tools/power-tuning/set_power_profile.sh --profile Performance --dry-run

# Fine-grained control: set explicit PkgWatt/SysWatt instead of a named profile
sudo tools/power-tuning/set_power_profile.sh --pkgWatt 25 --sysWatt 35

# Custom profile: any explicit parameters, passed straight through
sudo tools/power-tuning/set_power_profile.sh --profile Custom --pkgWatt 30 --sysWatt 40 --burstRatio 1.3

Tips for choosing a profile

• Start with the profile whose PkgWatt budget fits your power/thermal envelope, then step up one profile at a time until throughput stops improving.
• Each profile's default burst ratio is tuned for its budget; override with --burstRatio only if you need more responsiveness (higher) or a flatter, more predictable power/temperature (closer to 1.0).
• The PkgWatt cap is enforced on every platform. On silicon that also exposes a psys (SysWatt) domain, the whole-platform (SysWatt) limit tracks the same PkgWatt budget by default, or an explicit --sysWatt <W> value when you pass one alongside the profile. On silicon without a psys domain the SysWatt cap is skipped (PkgWatt only) and any --sysWatt is ignored.
• Measure while tuning: run turbostat (or the monitor-power-thermal skill) under your real workload to see PkgWatt/SysWatt and package temperature.
• The RAPL power cap is runtime-only and resets to firmware defaults on reboot, so the wattage limit is safe to experiment with. The intel_lpmd config the script writes persists on disk and is re-read by the daemon at the next boot, so the daemon-side tuning is not undone by a reboot (see Rollback). Re-run a lower profile to lower the cap immediately.
• For fine-grained control of exact PkgWatt/SysWatt values (instead of named profiles), use the Custom profile with the explicit pkg_watt/sys_watt/ burst_ratio/pl1_tau inputs described below.

Side Effects

Every profile is a trade-off. Use this to understand what changes — for better and worse — when you pick one, so there are no surprises in production.

By choice

General side effects to expect

• Thermals & acoustics: higher profiles raise package temperature and fan speed/noise; lower profiles run cooler and quieter (or fanless).
• Throttling: if cooling can't keep up, the firmware clamps sustained power below the profile's target — you'll see the "firmware clamped PL1" note and the effective (enforced) value in the report.
• Battery & energy: higher profiles shorten battery runtime and increase energy consumption; lower profiles extend both.
• Perceived responsiveness vs. throughput: burst headroom helps feel fast; the profile's PkgWatt budget drives long-running throughput.
• Brief management gap: applying a profile restarts intel_lpmd.service (~2 s) during which the daemon isn't actively managing CPU states.
• SysWatt reads 0.00: on some Core Ultra silicon the psys counter is frozen; the cap is still written but not observable via turbostat — use PkgWatt as the effective figure. This is a firmware limitation, not a failure.
• Partial revert on reboot: the RAPL power cap resets to firmware defaults on reboot (a built-in safety net if a profile turns out too aggressive), but the intel_lpmd config written to disk persists and is re-read by the daemon at the next boot. Restore the .orig config (see Rollback) to undo the daemon-side tuning.

Trigger Phrases

• set power profile
• apply power profile
• set profile to LowPower / BalancedLow / BalancedHigh / Performance / MaxPerformance
• switch to power profile
• set platform profile W
• use the low power / max performance profile
• list power profiles
• set platform power / set power envelope / change power envelope
• set package power limit / cap cpu package power
• set pkgwatt / set syswatt
• set PL1 and PL2
• set platform power to N watts
• tune tdp / set tdp
• set power to W with burst ratio

Required Inputs

• enib_home: absolute path to this repository root (default: current workspace root). On a host provisioned with Infrastructure Blueprint, the developer source tree lives at /opt/edge/developer, so enib_home is /opt/edge/developer on the target system.
• profile: one of LowPower, BalancedLow, BalancedHigh, Performance, MaxPerformance, or Custom (case-insensitive). Optional; defaults to BalancedHigh (20 W) when not supplied — the skill does not prompt for it. A named preset sets the PkgWatt budget for you; choose Custom to set an explicit power envelope with pkg_watt/sys_watt/pl1_tau (see below).
• pkg_watt: PkgWatt (PL1 sustained) target in watts. Only for Custom (a named preset sets PkgWatt itself, so it is rejected there). Must be a multiple of 5, from 5 up to the platform's cTDP Level 2 maximum (read from the CPU at runtime). When Custom is selected without pkg_watt, it defaults to the platform Nominal TDP (no prompt).
• burst_ratio: burst ratio (>= 1.0, optional). For a named profile, when omitted the profile's default is used (LowPower 1.25, BalancedLow 1.25, BalancedHigh 1.18, Performance 1.19, MaxPerformance 1.18); for Custom the default is 1.25. Overrides the default when supplied. PL2 = PkgWatt * burst_ratio, clamped to cTDP Level 2.
• sys_watt: psys/platform (SysWatt) cap in watts (optional). May be supplied alongside a named profile or Custom to override the SysWatt cap on psys-capable silicon; without it the SysWatt cap tracks the PkgWatt budget. When supplied, must be a multiple of 5 in [5, cTDP Level 2]. Ignored on platforms without a psys domain.
• pl1_tau: PL1 time window (tau) in seconds (optional, default 28).
• dry_run: true | false (default: false). When true, only the resolved plan is shown; nothing is applied.
• auto_confirm: true | false (default: false). When true, skip the confirmation gate.

Profile Table

Preconditions

Run silently without user prompts:

• Skill file exists and is readable:
  • test -f <enib_home>/skills/set-power-profile/SKILL.md
• The profile script exists and is executable:
  • test -x <enib_home>/tools/power-tuning/set_power_profile.sh
• Host is x86_64 with an Intel CPU (sanity check; non-fatal warning if not):
  • uname -m and grep -m1 -o 'GenuineIntel' /proc/cpuinfo
• msr-tools and the msr module are available (needed to probe psys support, read cTDP levels, and program RAPL MSRs):
  • command -v rdmsr && command -v wrmsr
  • if missing, warn that psys support cannot be probed reliably and the script will fall back to Panther Lake defaults; the PkgWatt estimate path may be used.
• Sudo (non-interactive — never prompt for sudo approval). This skill assumes passwordless sudo is already configured for the script (run the setup-agent-sudo prerequisite once per host). Do NOT ask the user for sudo approval, a password, or sudo -v at any point in the skill execution. You MAY run a silent sudo -n true for the report only, but never pause, prompt, or block on its result. dry_run=true needs no sudo (read-only). Never collect a password via prompts, env vars, scripts, or logs. See AGENTS.md.
• Determine the cTDP Level 2 maximum (upper bound for a Custom pkg_watt/sys_watt):
  • The script reads the cTDP MSRs internally and prints the resolved values (Config-TDP levels: Nominal=…W Level1=…W Level2=…W) in its output. Use CTDP_MAX=65 (Panther Lake fallback) as the reported ceiling for input validation before running; the script will clamp to the real value at runtime.

Defaults for missing inputs (do NOT prompt):

• If profile is not provided, default to BalancedHigh and continue — do not prompt.
• If profile=Custom and pkg_watt is missing, default to the platform Nominal TDP (from the CPU's Config-TDP MSRs; Panther Lake fallback if unreadable) — do not prompt.
• Use defaults for burst_ratio, sys_watt, pl1_tau, dry_run, and auto_confirm unless the user supplied them.

Input validation (fail closed before running the script):

• profile matches one of the five names or Custom (case-insensitive). Otherwise stop and list the valid profiles.
• burst_ratio (if supplied) is a number >= 1.0.
• With a named preset, pkg_watt is rejected (the preset sets PkgWatt); sys_watt is allowed as a platform-cap override.
• For Custom: pkg_watt is required — an integer, a multiple of 5, and 5 <= pkg_watt <= CTDP_MAX. Do not silently round; stop and report the valid range/step if invalid.
• If sys_watt is supplied (with a preset or Custom): integer, a multiple of 5, 5 <= sys_watt <= CTDP_MAX.
• pl1_tau (if supplied) is a positive number of seconds.

Steps

Terminal command rules (MUST follow for every command in this skill):

• Always invoke scripts by absolute path — never prefix with cd.
• Never combine cd with any output redirection (>, >>, 2>, 2>&1, | tee) in the same compound command — this triggers the VS Code "Compound command contains cd with output redirection" approval dialog. Run them as separate commands if both are needed.
• Never use $(...) command substitution in terminal commands — VS Code blocks them with a "Contains command_substitution" approval dialog. The scripts handle all internal computation themselves.

1. Resolve the plan (no writes yet):
   • PkgWatt = profile target (from the Profile Table; MaxPerformance = cTDP Level 2).
   • burst_ratio = supplied value or the profile default.
   • SysWatt cap = sys_watt if supplied, else PkgWatt (only applied on psys-capable silicon).
2. Determine psys (SysWatt) support (read-only best effort):
   • Supported when a powercap domain named psys exists under /sys/class/powercap/intel-rapl:*/name, or MSR_PLATFORM_POWER_LIMIT (0x65C) reads non-zero.
   • When supported, the script enforces the PkgWatt cap AND a SysWatt cap (the explicit sys_watt when given, otherwise tracking the PkgWatt budget).
   • When not supported, only the PkgWatt cap is enforced (the SysWatt domain does not exist on this platform, and any sys_watt is ignored).
3. Capture a pre-change RAPL snapshot for the report (read-only). Use individual cat commands — no $(...) substitution, no cd prefix. Read each file separately:
   • cat /sys/class/powercap/intel-rapl:0/name
   • cat /sys/class/powercap/intel-rapl:0/constraint_0_power_limit_uw
   • cat /sys/class/powercap/intel-rapl:0/constraint_1_power_limit_uw
   • cat /sys/class/powercap/intel-rapl:0/enabled
   • Repeat for :1 (psys) if present. Record the values for the post-change comparison.
4. Always execute a dry run first (read-only, no sudo, no writes):
   • Run <enib_home>/tools/power-tuning/set_power_profile.sh --profile <profile> [--pkgWatt <pkg_watt>] [--sysWatt <sys_watt>] [--burstRatio <burst_ratio>] [--pl1Tau <pl1_tau>] --dry-run and capture the resolved plan verbatim (it prints the effective explicit-target command line, the resolved PkgWatt/PL2/SysWatt values, and any firmware/cTDP clamping).
   • This step runs unconditionally on every invocation, including when auto_confirm=true.
5. Render the Planned Changes as a table built from the dry-run output (profile, PkgWatt target, resolved burst ratio, PL2, SysWatt cap, psys-supported yes/no, and any clamp note). Show it to the user before any write.
6. Confirmation gate — pause before any write:
   • If dry_run=true: stop here and record CONFIRMATION=dry_run_only. Do not apply.
   • Else if auto_confirm=true: log AUTO_CONFIRM=true and continue.
   • Else: present the tabulated Planned Changes and ask "Apply the profile (PkgWatt W, burstRatio ) on this host? (yes/no)". On anything other than yes/y (case-insensitive), stop and record CONFIRMATION=declined.
7. Apply (only after confirmation). set_power_profile.sh self-elevates with sudo -E internally when not root, so the agent calls it directly — no sudo prefix in the terminal command, which avoids the VS Code approval dialog. Build the argument list:
   • Base: <enib_home>/tools/power-tuning/set_power_profile.sh --profile <profile>
   • For Custom, also append --pkgWatt <pkg_watt> and, when supplied, --pl1Tau <pl1_tau> (default 28).
   • Append --sysWatt <sys_watt> only when the user supplied one.
   • Append --burstRatio <burst_ratio> only when the user supplied one (otherwise the script uses the profile default; for Custom the script default is 1.25).
   • Capture stdout/stderr verbatim and record the exit code.
8. Capture a post-change RAPL snapshot using the same individual cat commands as Step 3.

Validation

Validation section is criteria-only. Do not render the pass/fail results table here.

• Preconditions passed (script executable). Passwordless sudo is assumed pre-configured; the sudo probe is informational only and never blocks execution.
• profile validated against the five names; burst_ratio validated when supplied.
• A dry run was executed first on every invocation, and the Planned Changes table was rendered from its output before the confirmation gate.
• Confirmation gate outcome recorded as one of: confirmed, auto_confirm, declined, dry_run_only.
• Apply phase only executed when the outcome is confirmed or auto_confirm.
• When applied, the script exited with code 0.
• Post-change package RAPL PL1/PL2 reflect the profile PkgWatt (allowing for firmware/cTDP clamping); when psys is supported the psys domain reflects the SysWatt cap (the explicit sys_watt when given, otherwise the PkgWatt budget).
• Note: on platforms where the psys counter is frozen/unavailable, the SysWatt cap is written to the register but turbostat still reads SysWatt=0.00; this is a firmware limitation, not a failure.

Rollback

• The RAPL power cap (PL1/PL2 wattage) is runtime-only and reverts to firmware defaults on reboot.
• The intel_lpmd config the script writes persists on disk and is re-read by the daemon at the next boot, so it does NOT revert on its own.
• To revert immediately, re-run with a lower profile (e.g. LowPower) or a Custom envelope at the platform Nominal TDP (reported in the script output as Config-TDP levels: Nominal=…).
• set_power_profile.sh keeps a one-time .orig backup of any model-specific intel_lpmd config it overrides; restore it and restart intel_lpmd.service to return the daemon config to stock.

Safety Rules

• Never collect a sudo password and never prompt for sudo approval during skill execution; passwordless sudo is expected to be pre-configured (see the setup-agent-sudo prerequisite). Never collect a password via prompts, env vars, scripts, or logs.
• Never combine cd with output redirection (>, >>, 2>, 2>&1, | tee) in the same compound terminal command — VS Code blocks such commands with an approval dialog. Always use absolute paths and split commands if redirection is needed.
• Never use $(...) command substitution in terminal commands — VS Code blocks them with an approval dialog. Delegate all computation to the scripts themselves.
• Warn before applying a high profile (MaxPerformance) or a high burst_ratio on thermally constrained (e.g. fanless) enclosures; report package temperature via turbostat when available.
• The script restarts intel_lpmd.service to load the new profile; note the brief (~2 s) management gap to the user.
• Do not modify anything outside tools/power-tuning/ and the intel_lpmd config directory the script manages.

Expected Result Summary

Render the report as the following tables.

Run Metadata

Planned Changes

RAPL Snapshot (pre → post)

(omit when the outcome is declined or dry_run_only)

Validation Results

Failures and Troubleshooting

Troubleshooting Notes

• List the available profiles at any time with <enib_home>/tools/power-tuning/set_power_profile.sh --list.
• The skill never prompts for sudo approval. If the script fails because sudo needs a password, configure passwordless sudo out of band first by running the setup-agent-sudo prerequisite (installs a scoped entry via sudo visudo -f /etc/sudoers.d/set-power-profile):

  <user> ALL=(root) NOPASSWD: /home/<user>/enib/tools/power-tuning/set_power_profile.sh
  

  Never use NOPASSWD: ALL. If a sudo -v timestamp exists but is not honored (tty_tickets), make timestamps global: echo 'Defaults timestamp_type=global' | sudo tee /etc/sudoers.d/agent-timestamp && sudo chmod 0440 /etc/sudoers.d/agent-timestamp && sudo visudo -c.
• If rdmsr/wrmsr are missing: sudo apt-get install -y msr-tools and sudo modprobe msr. Without them psys support cannot be probed and the script uses Panther Lake defaults.
• If psys is reported "not supported": only the PkgWatt cap is applied (this platform has no psys/SysWatt domain), which is the expected behaviour on such silicon.
• If SysWatt still reads 0.00 in turbostat after applying: the platform (psys) RAPL counter is frozen/unpopulated on some Core Ultra platforms. This is a firmware limitation; use PkgWatt as the effective figure.
• If the script reports "firmware clamped PL1 to W": set Config-TDP Level 2 in BIOS to raise the ceiling.
• The RAPL power cap does not persist across reboot; to re-apply it automatically at boot, wrap the invocation in a systemd unit (out of scope for this skill). The intel_lpmd config the script writes does persist on disk and is re-read by the daemon at boot.