en Copyright 2015 Java http://kernelsources.org:8080/source/history/linux/tools/testing/selftests/clock-helpers.h#3b4128b9f374b4219eb716f4ad8a307bc7eb3d84 Merge tag 'timers-core-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipPull timer and timekeeping core updates from Thomas Gleixner: - Fix a subtly inconsistency in the timekeeping code, which fails to account for the monotonicity adjustment in ntp_error. For small changes of the clocksource multiplicator (+/-1) which are typically used by the NTP PLL this is hard to observe. But for larger adjustments, e.g. caused by a direct frequency setting through adjtimex() the one-time uncompensated offset is significant. Cure this by adjusting ntp_error with the resulting offset so that the discrepancy is smoothed away over time - Make tick length calculations correct in NTP. The timekeeping core takes the quantisation of the clocksource into account when calculating the tick length to compensate for the deviation of the nominal NTP_INTERVAL_LENGTH. While timekeeping gets this right, NTP is not aware of that, which means it operates on the nominal value and not on the actual value which is determined by the clock source frequency. The rounding of a coarse clocksource like the ACPI PM timer results in a +127 PPM deviation. Cure this by exposing the deviation to the NTP code so that it can operate on the same data as the timekeeping core. This is purely kernel internal. User space still sees the nominal tick lenght via adjtimex(). - The accuracy of the NTP adjustments is fairly approximate as the code assumes that the invocations are precisely in NTP interval frequency ticks and the final adjustment can over and under-run. Cure this by adjusting ntp_error by the intended skew on each tick to achieve the desired rate. - Handle the two competing skews of time offset and time adjustment correctly by calculating the conflict portion between the skews and adjusting both accordingly. - A set of updates and improvements for the selftests - The usual small fixes and improvements all over the place* tag 'timers-core-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (58 commits) selftests: timers: nsleep-lat: Check all calls to clock_nanosleep() and clock_gettime() selftests: timers: nsleep-lat: Reuse kselftest error numbers selftests: timers: nsleep-lat: Explicitly list the tested clocks selftests: timers: nsleep-lat: Use NSEC_PER_MSEC define for unreasonable latency selftests: timers: nanosleep: Report each test separately selftests: timers: nanosleep: Explicitly handle timer_delete() failure selftests: timers: nanosleep: Move all single clock tests out of the loop in main() selftests: timers: nanosleep: Reuse kselftest error numbers selftests: timers: nanosleep: Explicitly list the tested clocks selftests: timers: nanosleep: Drop output alignment selftests: timers: Use clock_name() and constants from clock-helpers.h selftests: Add clock-helpers.h timer_list: Use ktime_t over nanoseconds timer_list: Use standard 'long long' format placeholders hrtimer: Add a lockdep assertion to hrtimer_update_base() timekeeping: Use u32 for clock_was_set_seq timekeeping: Rename clockid_aux_valid() to clockid_is_aux_clock() hrtimer: Account nr_retries on recovered interrupt retries timers/itimer: Zero-init old itimerval before copy to userspace nohz: Replace dead select with choice default ... List of files: /linux/tools/testing/selftests/clock-helpers.h Wed, 19 Aug 2026 01:23:56 +0200 Linus Torvalds <torvalds@linux-foundation.org> http://kernelsources.org:8080/source/history/linux/tools/testing/selftests/clock-helpers.h#431012dd0a291bc135eb88d8a62d7424576800fa selftests: Add clock-helpers.hMultiple selftests duplicate various clock-related functionality.Add a new header to collect and deduplicate those.Signed-off-by: Thomas Weißschuh (Schneider Electric) <thomas.weissschuh@linutronix.de>Signed-off-by: Thomas Gleixner <tglx@kernel.org>Acked-by: John Stultz <jstultz@google.com>Link: https://patch.msgid.link/20260803-auxclock-nanosleep-prep-v2-6-910cbd485390@linutronix.de List of files: /linux/tools/testing/selftests/clock-helpers.h Mon, 03 Aug 2026 12:04:37 +0200 Thomas Weißschuh (Schneider Electric) <thomas.weissschuh@linutronix.de>