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sys_linux: stop sticking ticks as workaround for old kernels

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Drop the old workaround avoiding small changes in ticks needed to avoid
frequency steps due to inexact scaling of frequency vs ticks in kernels
before 2.6.18. chrony doesn't support such old kernels anymore.
This commit is contained in:
Miroslav Lichvar
2025-11-20 09:53:49 +01:00
parent b86c9d9c83
commit 8a2a1dab72
1 changed files with 0 additions and 15 deletions
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15
sys_linux.c
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@@ -139,21 +139,6 @@ set_frequency(double freq_ppm)
int required_delta_tick; int required_delta_tick;
required_delta_tick = round(freq_ppm / dhz); required_delta_tick = round(freq_ppm / dhz);
/* Older kernels (pre-2.6.18) don't apply the frequency offset exactly as
set by adjtimex() and a scaling constant (that depends on the internal
kernel HZ constant) would be needed to compensate for the error. Because
chronyd is closed loop it doesn't matter much if we don't scale the
required frequency, but we want to prevent thrashing between two states
when the system's frequency error is close to a multiple of USER_HZ. With
USER_HZ <= 250, the maximum frequency adjustment of 500 ppm overlaps at
least two ticks and we can stick to the current tick if it's next to the
required tick. */
if (sys_hz <= 250 && (required_delta_tick + 1 == current_delta_tick ||
required_delta_tick - 1 == current_delta_tick)) {
required_delta_tick = current_delta_tick;
}
required_freq = -(freq_ppm - dhz * required_delta_tick); required_freq = -(freq_ppm - dhz * required_delta_tick);
required_tick = nominal_tick - required_delta_tick; required_tick = nominal_tick - required_delta_tick;