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fan-control: power-tune COOL curve to the 60% efficiency knee

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Power/temp sweep (2026-06-05) located the cooling-per-watt knee at ~60%:
60->70% buys only -2C for +21W, and 70->100% buys 0C for +54W (the CPU
floors ~59C at cluster load, so more airflow does nothing). Re-tune the
COOL curve to cap its normal band at 60% (~303W, ~61C); 80/100% become a
high-load safety ramp (>=73/79C) before the 83C ceiling. QUIET unchanged
(already at the 281W / 4800rpm floor). Saves up to ~75W (~650 kWh/yr) vs
full-tilt for the last ~2C. Tests + design doc updated; verified live
(63C, 60%, ~267W).

[ci skip]

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Viktor Barzin 2026-06-05 06:43:21 +00:00
parent 17da37cea3
commit 99f9bf8d89
3 changed files with 54 additions and 24 deletions
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6
scripts/fan-control.sh
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@ -43,7 +43,11 @@ set -uo pipefail
: "${RUN_ONCE:=0}" # 1 => one iteration then exit (testing)
# Curves as "min_temp:pct" entries, descending; first whose min_temp <= temp wins.
COOL_CURVE=(74:100 68:85 61:65 53:45 0:25)
# COOL is power-tuned (2026-06-05 power/temp sweep): the cooling-per-watt knee is
# ~60% — beyond it airflow buys almost nothing (60->70% = +21W/-2°C, 70->100% =
# +54W/0°C; the CPU floors ~59°C at cluster load). So the normal band caps at 60%
# (~303W, ~61°C); 80/100% are a high-load safety ramp before the 83°C ceiling.
COOL_CURVE=(79:100 73:80 64:60 55:50 0:30)
QUIET_CURVE=(82:100 78:65 73:40 0:20)
log() { printf '%s %s\n' "$(date '+%Y-%m-%dT%H:%M:%S%z')" "$*"; }