pid_controller(9)

✨ NAME ✨

okay bestie, welcome to the pid_controller(9) page from the Kernel API Manual. The star of the show is pid_controller — literally a PID controller, no cap. 💅

🦋 SYNOPSIS 🦋

u32 pid_controller (struct thermal_zone_device *tz , int control_temp ,
u32 max_allocatable_power );

🌸 ARGUMENTS 🌸

• tz — the thermal zone we're operating in. that's the arena. 🏟️
• control_temp — the target temperature, in millicelsius. yes, milli. keep the units, bestie. 🌡️
• max_allocatable_power — the maximum allocatable power for this thermal zone. that's the ceiling. 🚧

💖 DESCRIPTION 💖

This PID controller increases the available power budget so the thermal zone's temperature gets as close as possible to control_temp — and if the temperature exceeds that target, it limits the power. slay, boundaries. ✋

k_po is the proportional term for when we're overshooting. k_pu is the proportional term for when we're undershooting. both iconic, both doing their job. ⚖️

integral_cutoff is a threshold — below it, we stop accumulating the error. The accumulated error only counts if the requested power will actually make the system warmer. 🔥 And if the system is mostly idle? there's no point in accumulating positive error, bestie. it's giving waste of energy. 🙈

🎀 RETURN 🎀

The power budget for the next period. that's the whole return bag. 💰✨

🔥 SEE ALSO 🔥

• Kernel file: ./drivers/thermal/gov_power_allocator.c — go read the source, iykyk. 📖
• mul_frac(9)
• div_frac(9)
• struct power_actor(9)
• struct power_allocator_params(9)
• estimate_sustainable_power(9)
• estimate_pid_constants(9)
• get_sustainable_power(9)
• power_actor_set_power(9)
• divvy_up_power(9)
• get_governor_trips(9)
• check_power_actors(9)
• power_allocator_bind(9)

mwah 💋 this page lives under ./drivers/thermal, dated October 2026, and it's pid_controller(9) — bye bestie, go budget that power responsibly. 🫶✨