cpufreq_driver_adjust_perf(9)

📦 version 7.3.1, in nixpkgs unstable

👑 cpufreq_driver_adjust_perf(9) — Kernel API Manual, bestie edition 🎀

okay so you're in the kernel API manual (cpufreq_driver_adjust_perf(9)) and you found the function that adjusts CPU performance level in one go. one go!! no half measures. let's get into it ✨

🌸 SYNOPSIS 🌸

void cpufreq_driver_adjust_perf (struct cpufreq_policy *policy ,
unsigned long min_perf , unsigned long target_perf , unsigned long
max_perf , unsigned long capacity );

like, five args, one call, no sleeping, we move 💅

🦋 ARGUMENTS 🦋

  • policy — the cpufreq policy object of the target CPU. it's giving "who am i doing this for" energy.
  • min_perf — the minimum (required) performance level, in units of capacity. the floor, the bare minimum, the "at least this much" 🥺
  • target_perf — the target (desired) performance level, in units of capacity. the dream. the goal. the main character number.
  • max_perf — the maximum (allowed) performance level, in units of capacity. the ceiling, the limit, the "bestie no further" 🛑
  • capacity — the capacity of the target CPU. iykyk.

💖 DESCRIPTION 💖

So basically: this carries out a fast performance level adjustment for the CPU represented by policy without sleeping. no naps. none. it's awake and it's working 🔥

The driver's ->adjust_perf callback invoked by this function must be suitable for calling from within RCU-sched read-side critical sections — and it's expected to program the processor to select suitable performance levels between min_perf and max_perf inclusive, and preferably close to target_perf going forward for the CPU represented by policy. so: stay in the range, aim for the vibe, look cute doing it 🌈

⚠️ Do NOT call this function if policy->fast_switch_enabled is unset. literally don't. that's the vibe check and you failed it 💀

Governors calling this function must guarantee two things, and these are non-negotiable fr fr:

  1. it will never be invoked twice in parallel for the same CPU, and
  2. it will never be called in parallel with either ->target or ->target_index or ->fast_switch for the same CPU.

no overlapping calls, no crossover episodes, no parallel chaos. periodt. 👑

🔍 SEE ALSO 🔍

Kernel file ./drivers/cpufreq/cpufreq.c — and the whole friend group, no one left out:

anyway that's the whole page, hope it ate 🍓 this one lives in ./drivers/cpufreq, dated October 2026, and it goes by cpufreq_driver_adjust_perf(9) — mwah, bye bestie! 💜🧚✨

📦 where this page comes from