STRUCT NTP_DATA(9)

💖 struct ntp_data(9) 💖

okay so bestie, welcome to the Kernel API Manual — this one's literally the struct ntp_data page and it's holding all the NTP state, like the whole personality of your kernel's clock sync in one struct. 🕰️✨

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✨ NAME ✨

struct ntp_data — the structure holding all NTP related state 🫶

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🦋 SYNOPSIS 🦋

struct ntp_data {
    unsigned long           tick_usec;
    u64 tick_length;
    int time_state;
    int time_status;
    s64 time_offset;
    s64 skew_delta;
    long time_constant;
    long time_maxerror;
    long time_esterror;
    s64 time_freq;
    time64_t time_reftime;
    long time_adjust;
    s64 time_adjust_frac;
    s64 ntp_tick_adj;
    s64 cs_tick_adj;
    time64_t ntp_next_leap_sec;
  #ifdef CONFIG_NTP_PPS;
    int pps_valid;
    long pps_tf[3];
    long pps_jitter;
    struct timespec64       pps_fbase;
    int pps_shift;
    int pps_intcnt;
    s64 pps_freq;
    long pps_stabil;
    long pps_calcnt;
    long pps_jitcnt;
    long pps_stbcnt;
    long pps_errcnt;
  #endif;
   };

ngl that #ifdef CONFIG_NTP_PPS; block is giving "only some of us are invited to the PPS party" energy 💅 — everything from pps_valid down to pps_errcnt only shows up when that config's on.

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🎀 Members 🎀

time to meet the cast, iykyk 💖

• tick_usec — the USER_HZ period, in microseconds ⏱️
• tick_length — tick length in ns, lowkey << NTP_SCALE_SHIFT-ed
• time_state — the state of the clock synchronization, like its current mood 🌈
• time_status — clock status bits
• time_offset — time adjustment, in nanoseconds
• skew_delta — per-tick phase slew rate for the coming second, measured in time_offset units (so: shifted-ns / HZ). Set by second_overflow. 👑
• time_constant — the PLL time constant
• time_maxerror — maximum error in microseconds, holding the NTP sync distance (that's NTP dispersion + delay / 2) 😭
• time_esterror — estimated error in microseconds, holding the NTP dispersion
• time_freq — frequency offset scaled nsecs/secs
• time_reftime — time at the last adjustment, in seconds
• time_adjust — the adjustment value
• time_adjust_frac — the sub-microsecond remainder of time_adjust being delivered, in ns << NTP_SCALE_SHIFT (and no, it is not divided by HZ 🫶)
• ntp_tick_adj — constant boot-param configurable NTP tick adjustment (upscaled)
• cs_tick_adj — a fixed per-second adjustment compensating for the difference between the nominal NTP interval and the real time taken by the clocksource's integer cycle_interval (upscaled). Set by the timekeeping core via ntp_clear. ⭐
• ntp_next_leap_sec — second value of the next pending leapsecond, or TIME64_MAX if there's no leap 🌸
• pps_valid — PPS signal watchdog counter 🐕
• pps_tf — PPS phase median filter
• pps_jitter — PPS current jitter, in nanoseconds
• pps_fbase — PPS beginning of the last freq interval
• pps_shift — PPS current interval duration in seconds (it's a shift value, bestie)
• pps_intcnt — PPS interval counter
• pps_freq — PPS frequency offset, in scaled ns/s
• pps_stabil — PPS current stability, in scaled ns/s
• pps_calcnt — PPS monitor: calibration intervals 📊
• pps_jitcnt — PPS monitor: jitter limit exceeded
• pps_stbcnt — PPS monitor: stability limit exceeded
• pps_errcnt — PPS monitor: calibration errors

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💜 Description 💜

Protected by the timekeeping locks. 🔒 that's it, that's the whole vibe — but fr fr do not go poking at this without holding them.

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🌟 SEE ALSO 🌟

Kernel file ./kernel/time/ntp.c, plus pps_clear(9), ntp_clear(9), ntp_get_next_leap(9), ntp_synced(9) — go read those, they ate 💅🔥

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and that's the page bestie!! 🎀 from ./kernel/time, dated October 2026 — the struct ntp_data(9) era, periodt. ✨🦋💖