viktor/infra
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

fan-control: continuous linear curve (replaces discrete step-bands)

Browse source 
Replace the step-band fan curve with a continuous linear ramp — the bands
flapped at edges (e.g. 45<->65%). Web-researched: linear + 2-3C hysteresis
is the homelab standard; PID is overkill for this slow thermal loop.
fan% now interpolates between env-tunable anchors:
  COOL  50C/30% -> 83C/100% (~2.1%/C; ~51% at the ~60C equilibrium)
  QUIET 68C/20% -> 83C/100% (near-silent until ~70C)
Both reach 100% at the 83C ceiling. Anti-oscillation: asymmetric
hysteresis (fc_decide) + a MIN_STEP (3%) min-change threshold.
41 bash tests green; deployed + verified live (59C -> 49%, smooth).

[ci skip]

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Viktor Barzin 2026-06-05 10:29:35 +00:00
parent 945c1936e3
commit 324f2dc3bf
4 changed files with 67 additions and 62 deletions
Download patch file Download diff file Expand all files Collapse all files

39
scripts/fan-control.sh
View file

@ -47,28 +47,31 @@ set -uo pipefail
: "${DRY_RUN:=0}" # 1 => log IPMI actions instead of executing
: "${RUN_ONCE:=0}" # 1 => one iteration then exit (testing)
# Curves as "min_temp:pct" entries, descending; first whose min_temp <= temp wins.
# COOL is power-tuned (2026-06-05 power/temp sweep): the cooling-per-watt knee is
# ~60% — beyond it airflow buys almost nothing (60->70% = +21W/-2°C, 70->100% =
# +54W/0°C; the CPU floors ~59°C at cluster load). So the normal band caps at 60%
# (~303W, ~61°C); 80/100% are a high-load safety ramp before the 83°C ceiling.
COOL_CURVE=(79:100 73:80 64:60 55:50 0:30)
QUIET_CURVE=(82:100 78:65 73:40 0:20)
# Continuous LINEAR fan curve (2026-06-05): fan% ramps proportionally with CPU
# temp between (T_LO,P_LO) and (T_HI,P_HI), clamped flat outside. Replaces the old
# discrete step-bands (which flapped at band edges — e.g. 45<->65%). Both modes
# reach 100% right at the 83°C ceiling. Anchors are env-tunable.
# COOL (garage empty): 30% @50°C .. 100% @83°C (~2.1%/°C; equilibrium ~60°C/~51%)
# QUIET (someone there): 20% @68°C .. 100% @83°C (near-silent until ~70°C)
# Web-researched: a linear curve + 2-3°C hysteresis is the homelab standard; PID is
# overkill for this slow thermal loop. See docs/plans/2026-06-04-pve-fan-control-design.md.
: "${COOL_T_LO:=50}"; : "${COOL_P_LO:=30}"; : "${COOL_T_HI:=83}"; : "${COOL_P_HI:=100}"
: "${QUIET_T_LO:=68}"; : "${QUIET_P_LO:=20}"; : "${QUIET_T_HI:=83}"; : "${QUIET_P_HI:=100}"
: "${MIN_STEP:=3}" # min fan-% change worth an IPMI write (anti-jitter on the smooth curve)
log() { printf '%s %s\n' "$(date '+%Y-%m-%dT%H:%M:%S%z')" "$*"; }
# ---- pure functions (no side effects; unit-tested) ----
# fc_curve <mode> <temp> -> fan percent
# fc_curve <mode> <temp> -> fan percent (continuous linear interpolation between
# the per-mode (T_LO,P_LO)..(T_HI,P_HI) anchors; clamped flat outside the range).
fc_curve() {
local mode="$1" temp="$2"
local -a curve
if [[ "$mode" == "quiet" ]]; then curve=("${QUIET_CURVE[@]}"); else curve=("${COOL_CURVE[@]}"); fi
local entry
for entry in "${curve[@]}"; do
if (( temp >= ${entry%%:*} )); then echo "${entry##*:}"; return 0; fi
done
echo "${curve[-1]##*:}"
local mode="$1" temp="$2" tlo plo thi phi
if [[ "$mode" == "quiet" ]]; then tlo=$QUIET_T_LO; plo=$QUIET_P_LO; thi=$QUIET_T_HI; phi=$QUIET_P_HI
else tlo=$COOL_T_LO; plo=$COOL_P_LO; thi=$COOL_T_HI; phi=$COOL_P_HI; fi
if (( temp <= tlo )); then echo "$plo"; return 0; fi
if (( temp >= thi )); then echo "$phi"; return 0; fi
echo $(( plo + ( (temp - tlo) * (phi - plo) + (thi - tlo) / 2 ) / (thi - tlo) )) # rounded
}
# fc_decide <mode> <temp> <current_pct> <deadband> -> fan percent
@ -230,7 +233,9 @@ main() {
local presence="cool"; [[ "$ha_mode" == "auto" ]] && presence="$(get_presence)"
local eff; if [[ "$ha_mode" == "manual" ]]; then eff="manual"; elif [[ "$ha_mode" == "auto" ]]; then eff="$presence"; else eff="$ha_mode"; fi
local pct; pct="$(fc_resolve "$ha_mode" "$temp" "$manual_pct" "$presence" "$current" "$DEADBAND")"
if (( pct != current )); then
# Only write when first-run or the change clears MIN_STEP (kills 1-2% jitter
# on the continuous curve; fc_decide already gives asymmetric hysteresis).
if (( current < 0 || pct - current >= MIN_STEP || current - pct >= MIN_STEP )); then
if set_manual "$pct"; then log "temp=${temp}C ha_mode=${ha_mode} eff=${eff} fan=${pct}% (was ${current}%)"; current="$pct"
else log "WARN set_manual ${pct}% failed"; fi
fi