diff options
| author | Miroslav Lichvar <[email protected]> | 2018-03-09 10:42:47 -0800 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2018-03-10 09:12:41 +0100 |
| commit | c2cda2a5bda9f1369c9d1ab54a20571c13cf2743 (patch) | |
| tree | c15708e16f272c90ec5a2632b4c9c47b11fcdf8f | |
| parent | 27263e8dc0f6fe27540a843611ec14a000591c41 (diff) | |
timekeeping/ntp: Don't align NTP frequency adjustments to ticks
When the timekeeping multiplier is changed, the NTP error is updated to
correct the clock for the delay between the tick and the update of the
clock. This error is corrected in later updates and the clock appears as
if the frequency was changed exactly on the tick.
Remove this correction to keep the point where the frequency is
effectively changed at the time of the update. This removes a major
source of the NTP error.
Signed-off-by: Miroslav Lichvar <[email protected]>
Signed-off-by: John Stultz <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Prarit Bhargava <[email protected]>
Cc: Richard Cochran <[email protected]>
Cc: Stephen Boyd <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | kernel/time/timekeeping.c | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index cd03317e7b57..c1a0ac17336e 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1860,8 +1860,6 @@ static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk, * xtime_nsec_2 = xtime_nsec_1 - offset * Which simplfies to: * xtime_nsec -= offset - * - * XXX - TODO: Doc ntp_error calculation. */ if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) { /* NTP adjustment caused clocksource mult overflow */ @@ -1872,7 +1870,6 @@ static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk, tk->tkr_mono.mult += mult_adj; tk->xtime_interval += interval; tk->tkr_mono.xtime_nsec -= offset; - tk->ntp_error -= (interval - offset) << tk->ntp_error_shift; } /* |