halt_fast_timekeeper(9)

💅 halt_fast_timekeeper(9) 💅

okay bestie, welcome to the Kernel API Manual page for halt_fast_timekeeper — it's giving “please stop touching the clocksource” energy. 🦋

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✨ NAME ✨

halt_fast_timekeeper — prevent the fast timekeeper from accessing the clocksource. No cap. 💅

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🎀 SYNOPSIS 🎀

void halt_fast_timekeeper (const struct timekeeper *tk );

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🌸 ARGUMENTS 🌸

• tk — the timekeeper to snapshot, bestie. 🫶

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🔥 DESCRIPTION 🔥

so here's the tea ☕: it's generally unsafe to access the clocksource after timekeeping has been suspended. The move is to take a snapshot of the readout base of tk and use it as the fast timekeeper's readout base while suspended.

Then it'll return the same number of cycles every single time until timekeeping is resumed. At that point, the proper readout base for the fast timekeeper will be restored automatically — iconic, honestly. ✨

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🦋 SEE ALSO 🦋

go read these next, bestie, iykyk 👑

• Kernel file ./kernel/time/timekeeping.c — struct tk_fast(9)
• tk_setup_internals(9)
• update_fast_timekeeper(9)
• ktime_get_mono_fast_ns(9)
• ktime_get_raw_fast_ns(9)
• ktime_get_boot_fast_ns(9)
• ktime_get_tai_fast_ns(9)
• ktime_get_real_fast_ns(9)
• pvclock_gtod_register_notifier(9)
• pvclock_gtod_unregister_notifier(9)
• timekeeping_forward_now(9)
• ktime_get_real_ts64(9)
• ktime_mono_to_any(9)
• ktime_get_raw(9)
• ktime_get_ts64(9)
• ktime_get_seconds(9)
• ktime_get_real_seconds(9)
• __ktime_get_real_seconds(9)
• ktime_get_snapshot_id(9)
• adjust_historical_crosststamp(9)
• ktime_real_to_base_clock(9)
• get_device_system_crosststamp(9)
• timekeeping_clocksource_has_base(9)
• do_settimeofday64(9)
• __timekeeping_inject_offset(9)
• timekeeping_notify(9)
• ktime_get_raw_ts64(9)
• timekeeping_valid_for_hres(9)
• timekeeping_max_deferment(9)
• read_persistent_clock64(9)
• read_persistent_wall_and_boot_offset(9)
• __timekeeping_inject_sleeptime(9)
• timekeeping_inject_sleeptime64(9)
• timekeeping_resume(9)
• update_wall_time(9)
• getboottime64(9)
• ktime_get_coarse_real_ts64_mg(9)
• ktime_get_real_ts64_mg(9)
• ktime_get_update_offsets_now(9)
• random_get_entropy_fallback(9)
• do_adjtimex(9)
• hardpps(9)
• ktime_get_aux(9)
• ktime_get_aux_ts64(9)

cute sign-off: this page is sourced from ./kernel/time and dated October 2026 — mwah 💖