adjust_jiffies(9)

💅 adjust_jiffies — Kernel API Manual, section 9

okay so bestie, buckle up, we're going into the kernel's cpufreq corner and this one's a lil function with a big job 🎀

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🌸 NAME 🌸

adjust_jiffies — it adjusts the system loops_per_jiffy, that's the whole vibe ✨

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🦋 SYNOPSIS 🦋

void adjust_jiffies (unsigned long val , struct cpufreq_freqs *ci );

like, two args, no return value, she's a void girlie and she knows it 💅

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🎀 ARGUMENTS 🎀

• val — this one has to be either CPUFREQ_PRECHANGE or CPUFREQ_POSTCHANGE. those are the only two moods she accepts, no cap. (and yes — the official docs literally write it as "CPUFREQ_PRECHANGE or CPUFREQ_POSTCHANGE", so pick one, don't get creative 🙈)
• ci — the frequency change info 💫 basically the little packet of details about the clock speed change that's happening.

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✨ DESCRIPTION ✨

so what she actually does: this function alters the system loops_per_jiffy for the clock speed change 🔥 that's it, that's the job, and she does it.

BUT — and this is the important part, bestie, listen — note that loops_per_jiffy cannot be updated on SMP systems, because each CPU might be scaled differently 😭 like, every core's out here living its own truth.

so use the arch per-CPU loops_per_jiffy value wherever possible. fr fr. that's the actual guidance, don't fight it 🫶

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👑 SEE ALSO 👑

kernel file ./drivers/cpufreq/cpufreq.c — and honestly the whole cpufreq friend group shows up here, so let's go down the list 🌈

• cpufreq_cpu_get(9)
• cpufreq_cpu_put(9)
• cpufreq_notify_transition(9)
• cpufreq_enable_fast_switch(9)
• cpufreq_disable_fast_switch(9)
• cpufreq_driver_resolve_freq(9)
• cpufreq_parse_governor(9)
• cpufreq_add_dev(9)
• cpufreq_out_of_sync(9)
• cpufreq_quick_get(9)
• cpufreq_quick_get_max(9)
• cpufreq_get_hw_max_freq(9)
• cpufreq_get(9)
• cpufreq_suspend(9)
• cpufreq_resume(9)
• cpufreq_driver_test_flags(9)
• cpufreq_get_current_driver(9)
• cpufreq_get_driver_data(9)
• cpufreq_register_notifier(9)
• cpufreq_unregister_notifier(9)
• cpufreq_driver_fast_switch(9)
• cpufreq_driver_adjust_perf(9)
• cpufreq_driver_has_adjust_perf(9)
• cpufreq_update_pressure(9)
• cpufreq_set_policy(9)
• cpufreq_update_policy(9)
• cpufreq_update_limits(9)
• cpufreq_register_driver(9)

every single one, we don't skip the boring ones, that's not how we treat the friend group 💖

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and that's the page!! source dir is ./drivers/cpufreq, and this lil beauty is dated October 2026 — adjust_jiffies(9), periodt 💅✨