* All units are in s and s/s, unless noted otherwise.
*/
#define CLOCK_MAX .128 /* default step threshold (s) */
-#define CLOCK_MINSTEP 900. /* default stepout threshold (s) */
+#define CLOCK_MINSTEP 300. /* default stepout threshold (s) */
#define CLOCK_PANIC 1000. /* default panic threshold (s) */
#define CLOCK_PHI 15e-6 /* max frequency error (s/s) */
#define CLOCK_PLL 16. /* PLL loop gain (log2) */
int pps_stratum; /* pps stratum */
int allow_panic = FALSE; /* allow panic correction */
int mode_ntpdate = FALSE; /* exit on first clock set */
+int freqcnt; /* initial frequency clamp */
/*
* Clock state machine variables
/*
* In FSET state this is the first update received and
* the frequency has been initialized. Adjust the phase,
- * but do not adjust the frequency until the next
- * update.
+ * but do not adjust the frequency until the holdoff
+ * counter decrements to zero.
*/
case EVNT_FSET:
+ freqcnt = clock_minstep;
rstclock(EVNT_SYNC, fp_offset);
break;
/*
* In FREQ state ignore updates until the stepout
* threshold. After that, compute the new frequency, but
- * do not adjust the phase or frequency until the next
- * update.
+ * do not adjust the frequency until the holdoff counter
+ * decrements to zero.
*/
case EVNT_FREQ:
if (mu < clock_minstep)
return (0);
clock_frequency = direct_freq(fp_offset);
+ freqcnt = clock_minstep;
rstclock(EVNT_SYNC, 0);
break;
/*
* We get here by default in SYNC and SPIK states. Here
* we compute the frequency update due to PLL and FLL
- * contributions.
+ * contributions. Note, we avoid frequency discipline at
+ * startup until the initial transient has subsided.
*/
default:
allow_panic = FALSE;
-
- /*
- * The FLL and PLL frequency gain constants
- * depend on the time constant and Allan
- * intercept. The PLL is always used, but
- * becomes ineffective above the Allan intercept
- * where the FLL becomes effective.
- */
- if (sys_poll >= allan_xpt)
- clock_frequency += (fp_offset -
- clock_offset) /
- max(ULOGTOD(sys_poll), mu) *
- CLOCK_FLL;
-
- /*
- * The PLL frequency gain (numerator) depends on
- * the minimum of the update interval and Allan
- * intercept. This reduces the PLL gain when the
- * FLL becomes effective.
- */
- etemp = min(ULOGTOD(allan_xpt), mu);
- dtemp = 4 * CLOCK_PLL * ULOGTOD(sys_poll);
- clock_frequency += fp_offset * etemp / (dtemp *
- dtemp);
+ if (freqcnt == 0) {
+
+ /*
+ * The FLL and PLL frequency gain constants
+ * depend on the time constant and Allan
+ * intercept. The PLL is always used, but
+ * becomes ineffective above the Allan intercept
+ * where the FLL becomes effective.
+ */
+ if (sys_poll >= allan_xpt)
+ clock_frequency += (fp_offset -
+ clock_offset) /
+ max(ULOGTOD(sys_poll), mu) *
+ CLOCK_FLL;
+
+ /*
+ * The PLL frequency gain (numerator) depends on
+ * the minimum of the update interval and Allan
+ * intercept. This reduces the PLL gain when the
+ * FLL becomes effective.
+ */
+ etemp = min(ULOGTOD(allan_xpt), mu);
+ dtemp = 4 * CLOCK_PLL * ULOGTOD(sys_poll);
+ clock_frequency += fp_offset * etemp / (dtemp *
+ dtemp);
+ }
rstclock(EVNT_SYNC, fp_offset);
break;
}
* lead to overflow problems. This might occur if some misguided
* lad set the step threshold to something ridiculous.
*/
- if (pll_control && kern_enable) {
+ if (pll_control && kern_enable && freqcnt == 0) {
/*
* We initialize the structure for the ntp_adjtime()
* offset with the clock jitter. If the offset is less than the
* clock jitter times a constant, then the averaging interval is
* increased, otherwise it is decreased. A bit of hysteresis
- * helps calm the dance. Works best using burst mode.
+ * helps calm the dance. Works best using burst mode. Don't
+ * fiddle with the poll during the startup clamp period.
*/
- if (fabs(clock_offset) < CLOCK_PGATE * clock_jitter) {
+ if (freqcnt > 0) {
+ tc_counter = 0;
+ } else if (fabs(clock_offset) < CLOCK_PGATE * clock_jitter) {
tc_counter += sys_poll;
if (tc_counter > CLOCK_LIMIT) {
tc_counter = CLOCK_LIMIT;
* NTPv3, NTPv4 does not declare unsynchronized after one day,
* since the dispersion check serves this function. Also,
* since the poll interval can exceed one day, the old test
- * would be counterproductive.
+ * would be counterproductive. During the startup clamp period, the
+ * time constant is clamkped at 2.
*/
sys_rootdisp += clock_phi;
+ if (freqcnt > 0)
+ freqcnt--;
#ifndef LOCKCLOCK
/*
* get out of Dodge quick.
*/
if (!ntp_enable || mode_ntpdate || (pll_control &&
- kern_enable))
+ kern_enable && freqcnt == 0))
return;
/*
* Implement the phase and frequency adjustments. The gain
* factor (denominator) increases with poll interval, so is
- * dominated by the FLL above the Allan intercept.
+ * dominated by the FLL above the Allan intercept. Note the
+ * reduced time constant at startup.
*/
- adjustment = clock_offset / (CLOCK_PLL * ULOGTOD(sys_poll));
+ if (freqcnt > 0)
+ adjustment = clock_offset / (CLOCK_PLL * 4);
+ else
+ adjustment = clock_offset / (CLOCK_PLL * ULOGTOD(sys_poll));
clock_offset -= adjustment;
adj_systime(adjustment + drift_comp);
#endif /* LOCKCLOCK */
double fp_offset
)
{
-
-#ifdef KERNEL_PLL
- /*
- * If the kernel is enabled, we need the residual offset to
- * calculate the frequency correction.
- */
- if (pll_control && kern_enable) {
- memset(&ntv, 0, sizeof(ntv));
- ntp_adjtime(&ntv);
-#ifdef STA_NANO
- clock_offset = ntv.offset / 1e9;
-#else /* STA_NANO */
- clock_offset = ntv.offset / 1e6;
-#endif /* STA_NANO */
- drift_comp = FREQTOD(ntv.freq);
- }
-#endif /* KERNEL_PLL */
set_freq((fp_offset - clock_offset) / (current_time -
clock_epoch) + drift_comp);
wander_resid = 0;
projects / thirdparty / ntp.git / commitdiff
