mirror of
https://github.com/torvalds/linux.git
synced 2026-09-14 16:10:02 +02:00
3b4128b9f3
- 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 hardly 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
-----BEGIN PGP SIGNATURE-----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=prJt
-----END PGP SIGNATURE-----
Merge tag 'timers-core-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull 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
...
|
||
|---|---|---|
| .. | ||
| asm-generic | ||
| cxl | ||
| drm | ||
| fwctl | ||
| linux | ||
| misc | ||
| mtd | ||
| rdma | ||
| regulator | ||
| scsi | ||
| sound | ||
| video | ||
| xen | ||
| Kbuild | ||