mseries-power-tune

#!/bin/bash
# Opt-in, reversible userspace power trims for the j314s (elementary OS 9, Aurora kernel).
#
#   mseries-power-tune list                 items, what they do, whether they are applied
#   mseries-power-tune status               same as list, plus the live unit/sysfs state
#   mseries-power-tune apply ITEM...        apply items (root); prior state is saved first
#   mseries-power-tune revert ITEM...       restore exactly the saved prior state (root)
#   mseries-power-tune revert-all           revert every applied item
#   add --dry-run before the command to print what would change without touching anything
#
# Scope rules (see mseries/power/OPTIMIZE-2026-10-18.md):
#   * nothing here touches display (brightness, refresh, VRR, DPMS), audio (PipeWire, WirePlumber,
#     speakersafetyd), the kernel, kernel parameters or the bootloader; a unit guard refuses those names;
#   * every item records the previous state under $STATE before changing it, and `revert` restores it;
#   * none of these is a measured watt saving; measure with power_ab.py before claiming one.
set -euo pipefail
shopt -s nullglob

SYS=${MSERIES_SYS:-/sys}
PROC=${MSERIES_PROC:-/proc}
STATE=${MSERIES_TUNE_STATE:-/var/lib/mseries/power-tune}
SYSTEMCTL=${MSERIES_SYSTEMCTL:-systemctl}
DRY=0

ITEMS=(cups-browsed rpcbind smartd dock-lan-wake)

describe() {
  case $1 in
    cups-browsed) echo "stop cups-browsed (network printer auto-discovery; no queues are configured)";;
    rpcbind) echo "stop rpcbind service+socket (NFS/RPC portmapper; refused while an NFS mount exists)";;
    smartd) echo "stop smartmontools (SMART polling every 30 min; loses disk-health warnings) [proposed only]";;
    dock-lan-wake) echo "disable wake-from-sleep on USB Ethernet adapters (dock LAN), runtime only [sleep-only effect]";;
    *) return 1;;
  esac
}

die() { echo "mseries-power-tune: $*" >&2; exit 1; }

# Refuse anything that belongs to the display, audio or session stack, whatever an item says.
guard_unit() {
  case $1 in
    *pipewire*|*wireplumber*|*speakersafety*|*pulse*|*alsa*|*gala*|*gdm*|*lightdm*|*display*|*colord*|*geoclue*|*backlight*|*brightness*)
      die "refusing to touch $1: display/audio/session units are out of scope";;
  esac
}

run() {
  if (( DRY )); then echo "would run: $*"; else "$@"; fi
}

unit_enabled() { "$SYSTEMCTL" is-enabled "$1" 2>/dev/null || true; }
unit_active() { "$SYSTEMCTL" is-active "$1" 2>/dev/null || true; }

save_units() { # item unit...
  local item=$1 u f
  shift
  for u in "$@"; do guard_unit "$u"; done
  f=$STATE/$item.prev
  if (( DRY )); then echo "would save prior state of $* to $f"; return; fi
  mkdir -p "$STATE"
  : > "$f.tmp"
  for u in "$@"; do printf 'unit %s %s %s\n' "$u" "$(unit_enabled "$u")" "$(unit_active "$u")" >> "$f.tmp"; done
  mv "$f.tmp" "$f"
}

restore_units() { # item
  local f=$STATE/$1.prev kind u en ac
  [[ -f $f ]] || die "$1 is not applied (no $f)"
  while read -r kind u en ac; do
    [[ $kind == unit ]] || continue
    guard_unit "$u"
    [[ $en == enabled ]] && run "$SYSTEMCTL" enable "$u"
    [[ $ac == active ]] && run "$SYSTEMCTL" start "$u"
  done < "$f"
  run rm -f "$f"
}

nfs_mounted() { grep -qE '[[:space:]]nfs4?[[:space:]]' "$PROC/mounts"; }

usb_lan_wakeups() {
  local d
  for d in "$SYS"/bus/usb/devices/*; do
    [[ -f $d/power/wakeup ]] || continue
    # USB interfaces bound to an Ethernet driver (r8152, ax88179_178a, cdc_ether) mark their parent device.
    if compgen -G "$d/*:*/net/*" >/dev/null; then echo "$d"; fi
  done
}

apply_item() {
  local u
  describe "$1" >/dev/null || die "unknown item $1 (try: list)"
  # Idempotent: applying an applied item keeps the first saved prior state (A/B arms re-apply).
  if [[ -f $STATE/$1.prev ]]; then echo "$1 already applied"; return 0; fi
  case $1 in
    cups-browsed)
      save_units "$1" cups-browsed.service
      run "$SYSTEMCTL" disable --now cups-browsed.service;;
    rpcbind)
      nfs_mounted && die "an NFS filesystem is mounted; rpcbind stays"
      save_units "$1" rpcbind.socket rpcbind.service
      run "$SYSTEMCTL" disable --now rpcbind.socket rpcbind.service;;
    smartd)
      save_units "$1" smartmontools.service
      run "$SYSTEMCTL" disable --now smartmontools.service;;
    dock-lan-wake)
      local f=$STATE/$1.prev
      if (( DRY )); then
        for u in $(usb_lan_wakeups); do echo "would write disabled to $u/power/wakeup (was $(cat "$u/power/wakeup"))"; done
        return
      fi
      mkdir -p "$STATE"; : > "$f.tmp"
      for u in $(usb_lan_wakeups); do
        printf 'wakeup %s %s\n' "$u" "$(cat "$u/power/wakeup")" >> "$f.tmp"
        printf disabled > "$u/power/wakeup"
      done
      mv "$f.tmp" "$f";;
    *) die "unknown item $1 (try: list)";;
  esac
  (( DRY )) || echo "applied $1"
}

revert_item() {
  local f=$STATE/$1.prev kind path val
  describe "$1" >/dev/null || die "unknown item $1"
  [[ -f $f ]] || die "$1 is not applied (no $f)"
  if grep -q '^wakeup ' "$f"; then
    while read -r kind path val; do
      [[ $kind == wakeup && -f $path/power/wakeup ]] || continue
      if (( DRY )); then echo "would write $val to $path/power/wakeup"; else printf '%s' "$val" > "$path/power/wakeup"; fi
    done < "$f"
    run rm -f "$f"
  else
    restore_units "$1"
  fi
  (( DRY )) || echo "reverted $1"
}

show() {
  local i mark
  for i in "${ITEMS[@]}"; do
    if [[ -f $STATE/$i.prev ]]; then mark=applied; else mark=-; fi
    printf '%-14s %-8s %s\n' "$i" "$mark" "$(describe "$i")"
  done
}

status() {
  local u d
  show
  echo "--- live state"
  for u in cups.service cups-browsed.service rpcbind.service rpcbind.socket smartmontools.service; do
    printf '%-22s %-10s %s\n' "$u" "$(unit_enabled "$u")" "$(unit_active "$u")"
  done
  for d in $(usb_lan_wakeups); do printf 'usb-lan %s wakeup=%s\n' "${d##*/}" "$(cat "$d/power/wakeup")"; done
}

need_root() {
  (( DRY )) && return 0
  [[ ${MSERIES_TUNE_ALLOW_NONROOT:-0} == 1 ]] && return 0
  (( EUID == 0 )) || die "needs root (try sudo), or use --dry-run"
}

[[ ${1:-} == --dry-run ]] && { DRY=1; shift; }
cmd=${1:-list}
shift || true
case $cmd in
  list) show;;
  status) status;;
  apply) need_root; (( $# )) || die "apply which item?"; for i in "$@"; do apply_item "$i"; done;;
  revert) need_root; (( $# )) || die "revert which item?"; for i in "$@"; do revert_item "$i"; done;;
  revert-all) need_root; for i in "${ITEMS[@]}"; do [[ -f $STATE/$i.prev ]] && revert_item "$i"; done; true;;
  -h|--help|help) sed -n '2,16p' "$0";;
  *) die "unknown command $cmd";;
esac