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timekeeping: Read NTP tick length only once

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No point in reading it a second time when the comparison fails.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-1-554456a44a15@linutronix.de
This commit is contained in:
Thomas Gleixner 2024-10-09 10:28:54 +02:00
parent 2e529e637c
commit 14f1e3b3df
1 changed files with 3 additions and 2 deletions
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5
kernel/time/timekeeping.c
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@ -2161,16 +2161,17 @@ static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
*/
static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
{
u64 ntp_tl = ntp_tick_length();
u32 mult;
/*
* Determine the multiplier from the current NTP tick length.
* Avoid expensive division when the tick length doesn't change.
*/
if (likely(tk->ntp_tick == ntp_tick_length())) {
if (likely(tk->ntp_tick == ntp_tl)) {
mult = tk->tkr_mono.mult - tk->ntp_err_mult;
} else {
tk->ntp_tick = ntp_tick_length();
tk->ntp_tick = ntp_tl;
mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
tk->xtime_remainder, tk->cycle_interval);
}