/** * timekeeper_ids - IDs for various time keepers in the kernel * @TIMEKEEPER_CORE: The central core timekeeper managing system time * @TIMEKEEPER_AUX_FIRST: The first AUX timekeeper * @TIMEKEEPER_AUX_LAST: The last AUX timekeeper * @TIMEKEEPERS_MAX: The maximum number of timekeepers managed
*/ enum timekeeper_ids {
TIMEKEEPER_CORE, #ifdef CONFIG_POSIX_AUX_CLOCKS
TIMEKEEPER_AUX_FIRST,
TIMEKEEPER_AUX_LAST = TIMEKEEPER_AUX_FIRST + MAX_AUX_CLOCKS - 1, #endif
TIMEKEEPERS_MAX,
};
/** * struct tk_read_base - base structure for timekeeping readout * @clock: Current clocksource used for timekeeping. * @mask: Bitmask for two's complement subtraction of non 64bit clocks * @cycle_last: @clock cycle value at last update * @mult: (NTP adjusted) multiplier for scaled math conversion * @shift: Shift value for scaled math conversion * @xtime_nsec: Shifted (fractional) nano seconds offset for readout * @base: ktime_t (nanoseconds) base time for readout * @base_real: Nanoseconds base value for clock REALTIME readout * * This struct has size 56 byte on 64 bit. Together with a seqcount it * occupies a single 64byte cache line. * * The struct is separate from struct timekeeper as it is also used * for the fast NMI safe accessors. * * @base_real is for the fast NMI safe accessor to allow reading clock * realtime from any context.
*/ struct tk_read_base { struct clocksource *clock;
u64 mask;
u64 cycle_last;
u32 mult;
u32 shift;
u64 xtime_nsec;
ktime_t base;
u64 base_real;
};
/** * struct timekeeper - Structure holding internal timekeeping values. * @tkr_mono: The readout base structure for CLOCK_MONOTONIC * @xtime_sec: Current CLOCK_REALTIME time in seconds * @ktime_sec: Current CLOCK_MONOTONIC time in seconds * @wall_to_monotonic: CLOCK_REALTIME to CLOCK_MONOTONIC offset * @offs_real: Offset clock monotonic -> clock realtime * @offs_boot: Offset clock monotonic -> clock boottime * @offs_tai: Offset clock monotonic -> clock tai * @offs_aux: Offset clock monotonic -> clock AUX * @coarse_nsec: The nanoseconds part for coarse time getters * @id: The timekeeper ID * @tkr_raw: The readout base structure for CLOCK_MONOTONIC_RAW * @raw_sec: CLOCK_MONOTONIC_RAW time in seconds * @clock_was_set_seq: The sequence number of clock was set events * @cs_was_changed_seq: The sequence number of clocksource change events * @clock_valid: Indicator for valid clock * @monotonic_to_boot: CLOCK_MONOTONIC to CLOCK_BOOTTIME offset * @monotonic_to_aux: CLOCK_MONOTONIC to CLOCK_AUX offset * @cycle_interval: Number of clock cycles in one NTP interval * @xtime_interval: Number of clock shifted nano seconds in one NTP * interval. * @xtime_remainder: Shifted nano seconds left over when rounding * @cycle_interval * @raw_interval: Shifted raw nano seconds accumulated per NTP interval. * @next_leap_ktime: CLOCK_MONOTONIC time value of a pending leap-second * @ntp_tick: The ntp_tick_length() value currently being * used. This cached copy ensures we consistently * apply the tick length for an entire tick, as * ntp_tick_length may change mid-tick, and we don't * want to apply that new value to the tick in * progress. * @ntp_error: Difference between accumulated time and NTP time in ntp * shifted nano seconds. * @ntp_error_shift: Shift conversion between clock shifted nano seconds and * ntp shifted nano seconds. * @ntp_err_mult: Multiplication factor for scaled math conversion * @skip_second_overflow: Flag used to avoid updating NTP twice with same second * @tai_offset: The current UTC to TAI offset in seconds * * Note: For timespec(64) based interfaces wall_to_monotonic is what * we need to add to xtime (or xtime corrected for sub jiffy times) * to get to monotonic time. Monotonic is pegged at zero at system * boot time, so wall_to_monotonic will be negative, however, we will * ALWAYS keep the tv_nsec part positive so we can use the usual * normalization. * * wall_to_monotonic is moved after resume from suspend for the * monotonic time not to jump. We need to add total_sleep_time to * wall_to_monotonic to get the real boot based time offset. * * wall_to_monotonic is no longer the boot time, getboottime must be * used instead. * * @monotonic_to_boottime is a timespec64 representation of @offs_boot to * accelerate the VDSO update for CLOCK_BOOTTIME. * * @offs_aux is used by the auxiliary timekeepers which do not utilize any * of the regular timekeeper offset fields. * * @monotonic_to_aux is a timespec64 representation of @offs_aux to * accelerate the VDSO update for CLOCK_AUX. * * The cacheline ordering of the structure is optimized for in kernel usage of * the ktime_get() and ktime_get_ts64() family of time accessors. Struct * timekeeper is prepended in the core timekeeping code with a sequence count, * which results in the following cacheline layout: * * 0: seqcount, tkr_mono * 1: xtime_sec ... id * 2: tkr_raw, raw_sec * 3,4: Internal variables * * Cacheline 0,1 contain the data which is used for accessing * CLOCK_MONOTONIC/REALTIME/BOOTTIME/TAI, while cacheline 2 contains the * data for accessing CLOCK_MONOTONIC_RAW. Cacheline 3,4 are internal * variables which are only accessed during timekeeper updates once per * tick.
*/ struct timekeeper { /* Cacheline 0 (together with prepended seqcount of timekeeper core): */ struct tk_read_base tkr_mono;
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