STRUCT SYSTEM_TIME_SNAPSHOT(9)

💅 NAME

struct system_time_snapshot — bestie, it's a simultaneous time capture 🫶 like it grabs the monotonic raw time, a selected CLOCK_*, and the clocksource counter value all in one go, no cap.

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✨ SYNOPSIS ✨

struct system_time_snapshot {
    u64 cycles;
    u64 hw_cycles;
    ktime_t systime;
    ktime_t monoraw;
    enum clocksource_ids    cs_id;
    enum clocksource_ids    hw_csid;
    u32 clock_was_set_seq;
    u8 cs_was_changed_seq;
    u8 valid;
 };

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🎀 MEMBERS 🎀

🌸 the member breakdown, iykyk

• cycles — the clocksource counter value that's literally what produces the system times 💫
• hw_cycles — for derived clocksources, this is the hardware counter value that cycles was derived from 🦋
• systime — the system time of whichever CLOCK ID you selected 👑
• monoraw — the monotonic raw system time ⭐
• cs_id — the clocksource ID, iconic, no notes 💅
• hw_csid — the clocksource ID of the underlying hardware counter for derived clocksources that implement the read_snapshot callback 🔥
• clock_was_set_seq — the sequence number of clock-was-set events 🕰️
• cs_was_changed_seq — the sequence number of clocksource change events 🔄
• valid — true if the snapshot is valid ✅ like, the vibe check result fr fr

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💖 DESCRIPTION 💖

Okay so monoraw is CLOCK_MONOTONIC_RAW for system time CLOCK ids. 🫶

But for CLOCK_AUX$N clock ids, it's the monotonic raw time related to the AUX clock — which is CLOCK_MONOTONIC_RAW plus an AUX clock specific offset. 🧚 tiny little offset, big main character energy, you get it.

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🌈 SEE ALSO 🌈

Kernel file ./include/linux/timekeeping.h and honestly the whole friend group:

• ktime_get_real(9)
• ktime_get_boottime(9)
• ktime_get_clocktai(9)
• ktime_mono_to_real(9)
• ktime_get_ns(9)
• ktime_get_real_ns(9)
• ktime_get_boottime_ns(9)
• ktime_get_clocktai_ns(9)
• ktime_get_raw_ns(9)
• struct system_counterval_t(9)
• struct system_device_crosststamp(9)

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ok that's the whole page bestie, go read the source, it's giving main character kernel file 💀✨

Lots of love from ./include/linux 💜 — October 2026 edition, struct system_time_snapshot(9), periodt. 🎀