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authorDenys Vlasenko <vda.linux@googlemail.com>2021-02-21 09:05:48 +0100
committerDenys Vlasenko <vda.linux@googlemail.com>2021-02-21 09:05:48 +0100
commit423c4c25d8496a6e784b4ebbbaf1a6f4ae490f9b (patch)
tree980cd641ec7e0b65089b683794eb19090b741a24 /networking
parent5024d862551a762f8e95d887830710cd32c03fb8 (diff)
downloadbusybox-423c4c25d8496a6e784b4ebbbaf1a6f4ae490f9b.tar.gz
ntpd: remove unused USING_INITIAL_FREQ_ESTIMATION code
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'networking')
-rw-r--r--networking/ntpd.c184
1 files changed, 2 insertions, 182 deletions
diff --git a/networking/ntpd.c b/networking/ntpd.c
index 8c9e59de1..62543ad2f 100644
--- a/networking/ntpd.c
+++ b/networking/ntpd.c
@@ -373,8 +373,7 @@ typedef struct {
} peer_t;
-#define USING_KERNEL_PLL_LOOP 1
-#define USING_INITIAL_FREQ_ESTIMATION 0
+#define USING_KERNEL_PLL_LOOP 1
enum {
OPT_n = (1 << 0),
@@ -657,104 +656,11 @@ filter_datapoints(peer_t *p)
double sum, wavg;
datapoint_t *fdp;
-#if 0
/* Simulations have shown that use of *averaged* offset for p->filter_offset
* is in fact worse than simply using last received one: with large poll intervals
* (>= 2048) averaging code uses offset values which are outdated by hours,
* and time/frequency correction goes totally wrong when fed essentially bogus offsets.
*/
- int got_newest;
- double minoff, maxoff, w;
- double x = x; /* for compiler */
- double oldest_off = oldest_off;
- double oldest_age = oldest_age;
- double newest_off = newest_off;
- double newest_age = newest_age;
-
- fdp = p->filter_datapoint;
-
- minoff = maxoff = fdp[0].d_offset;
- for (i = 1; i < NUM_DATAPOINTS; i++) {
- if (minoff > fdp[i].d_offset)
- minoff = fdp[i].d_offset;
- if (maxoff < fdp[i].d_offset)
- maxoff = fdp[i].d_offset;
- }
-
- idx = p->datapoint_idx; /* most recent datapoint's index */
- /* Average offset:
- * Drop two outliers and take weighted average of the rest:
- * most_recent/2 + older1/4 + older2/8 ... + older5/32 + older6/32
- * we use older6/32, not older6/64 since sum of weights should be 1:
- * 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/32 = 1
- */
- wavg = 0;
- w = 0.5;
- /* n-1
- * --- dispersion(i)
- * filter_dispersion = \ -------------
- * / (i+1)
- * --- 2
- * i=0
- */
- got_newest = 0;
- sum = 0;
- for (i = 0; i < NUM_DATAPOINTS; i++) {
- VERB5 {
- bb_error_msg("datapoint[%d]: off:%f disp:%f(%f) age:%f%s",
- i,
- fdp[idx].d_offset,
- fdp[idx].d_dispersion, dispersion(&fdp[idx]),
- G.cur_time - fdp[idx].d_recv_time,
- (minoff == fdp[idx].d_offset || maxoff == fdp[idx].d_offset)
- ? " (outlier by offset)" : ""
- );
- }
-
- sum += dispersion(&fdp[idx]) / (2 << i);
-
- if (minoff == fdp[idx].d_offset) {
- minoff -= 1; /* so that we don't match it ever again */
- } else
- if (maxoff == fdp[idx].d_offset) {
- maxoff += 1;
- } else {
- oldest_off = fdp[idx].d_offset;
- oldest_age = G.cur_time - fdp[idx].d_recv_time;
- if (!got_newest) {
- got_newest = 1;
- newest_off = oldest_off;
- newest_age = oldest_age;
- }
- x = oldest_off * w;
- wavg += x;
- w /= 2;
- }
-
- idx = (idx - 1) & (NUM_DATAPOINTS - 1);
- }
- p->filter_dispersion = sum;
- wavg += x; /* add another older6/64 to form older6/32 */
- /* Fix systematic underestimation with large poll intervals.
- * Imagine that we still have a bit of uncorrected drift,
- * and poll interval is big (say, 100 sec). Offsets form a progression:
- * 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 - 0.7 is most recent.
- * The algorithm above drops 0.0 and 0.7 as outliers,
- * and then we have this estimation, ~25% off from 0.7:
- * 0.1/32 + 0.2/32 + 0.3/16 + 0.4/8 + 0.5/4 + 0.6/2 = 0.503125
- */
- x = oldest_age - newest_age;
- if (x != 0) {
- x = newest_age / x; /* in above example, 100 / (600 - 100) */
- if (x < 1) { /* paranoia check */
- x = (newest_off - oldest_off) * x; /* 0.5 * 100/500 = 0.1 */
- wavg += x;
- }
- }
- p->filter_offset = wavg;
-
-#else
-
fdp = p->filter_datapoint;
idx = p->datapoint_idx; /* most recent datapoint's index */
@@ -777,7 +683,6 @@ filter_datapoints(peer_t *p)
}
wavg /= NUM_DATAPOINTS;
p->filter_dispersion = sum;
-#endif
/* +----- -----+ ^ 1/2
* | n-1 |
@@ -1572,8 +1477,6 @@ update_local_clock(peer_t *p)
double abs_offset;
#if !USING_KERNEL_PLL_LOOP
double freq_drift;
-#endif
-#if !USING_KERNEL_PLL_LOOP || USING_INITIAL_FREQ_ESTIMATION
double since_last_update;
#endif
double etemp, dtemp;
@@ -1603,63 +1506,15 @@ update_local_clock(peer_t *p)
* action is and defines how the system reacts to large time
* and frequency errors.
*/
-#if !USING_KERNEL_PLL_LOOP || USING_INITIAL_FREQ_ESTIMATION
- since_last_update = recv_time - G.reftime;
-#endif
#if !USING_KERNEL_PLL_LOOP
+ since_last_update = recv_time - G.reftime;
freq_drift = 0;
#endif
-#if USING_INITIAL_FREQ_ESTIMATION
- if (G.discipline_state == STATE_FREQ) {
- /* Ignore updates until the stepout threshold */
- if (since_last_update < WATCH_THRESHOLD) {
- VERB4 bb_error_msg("measuring drift, datapoint ignored, %f sec remains",
- WATCH_THRESHOLD - since_last_update);
- return 0; /* "leave poll interval as is" */
- }
-# if !USING_KERNEL_PLL_LOOP
- freq_drift = (offset - G.last_update_offset) / since_last_update;
-# endif
- }
-#endif
/* There are two main regimes: when the
* offset exceeds the step threshold and when it does not.
*/
if (abs_offset > STEP_THRESHOLD) {
-#if 0
- double remains;
-
-// This "spike state" seems to be useless, peer selection already drops
-// occassional "bad" datapoints. If we are here, there were _many_
-// large offsets. When a few first large offsets are seen,
-// we end up in "no valid datapoints, no peer selected" state.
-// Only when enough of them are seen (which means it's not a fluke),
-// we end up here. Looks like _our_ clock is off.
- switch (G.discipline_state) {
- case STATE_SYNC:
- /* The first outlyer: ignore it, switch to SPIK state */
- VERB3 bb_error_msg("update from %s: offset:%+f, spike%s",
- p->p_dotted, offset,
- "");
- G.discipline_state = STATE_SPIK;
- return -1; /* "decrease poll interval" */
-
- case STATE_SPIK:
- /* Ignore succeeding outlyers until either an inlyer
- * is found or the stepout threshold is exceeded.
- */
- remains = WATCH_THRESHOLD - since_last_update;
- if (remains > 0) {
- VERB3 bb_error_msg("update from %s: offset:%+f, spike%s",
- p->p_dotted, offset,
- ", datapoint ignored");
- return -1; /* "decrease poll interval" */
- }
- /* fall through: we need to step */
- } /* switch */
-#endif
-
/* Step the time and clamp down the poll interval.
*
* In NSET state an initial frequency correction is
@@ -1694,12 +1549,6 @@ update_local_clock(peer_t *p)
recv_time += offset;
-#if USING_INITIAL_FREQ_ESTIMATION
- if (G.discipline_state == STATE_NSET) {
- set_new_values(STATE_FREQ, /*offset:*/ 0, recv_time);
- return 1; /* "ok to increase poll interval" */
- }
-#endif
abs_offset = offset = 0;
set_new_values(STATE_SYNC, offset, recv_time);
} else { /* abs_offset <= STEP_THRESHOLD */
@@ -1726,39 +1575,10 @@ update_local_clock(peer_t *p)
*/
exit(0);
}
-#if USING_INITIAL_FREQ_ESTIMATION
- /* This is the first update received and the frequency
- * has not been initialized. The first thing to do
- * is directly measure the oscillator frequency.
- */
- set_new_values(STATE_FREQ, offset, recv_time);
-#else
set_new_values(STATE_SYNC, offset, recv_time);
-#endif
VERB4 bb_simple_error_msg("transitioning to FREQ, datapoint ignored");
return 0; /* "leave poll interval as is" */
-#if 0 /* this is dead code for now */
- case STATE_FSET:
- /* This is the first update and the frequency
- * has been initialized. Adjust the phase, but
- * don't adjust the frequency until the next update.
- */
- set_new_values(STATE_SYNC, offset, recv_time);
- /* freq_drift remains 0 */
- break;
-#endif
-
-#if USING_INITIAL_FREQ_ESTIMATION
- case STATE_FREQ:
- /* since_last_update >= WATCH_THRESHOLD, we waited enough.
- * Correct the phase and frequency and switch to SYNC state.
- * freq_drift was already estimated (see code above)
- */
- set_new_values(STATE_SYNC, offset, recv_time);
- break;
-#endif
-
default:
#if !USING_KERNEL_PLL_LOOP
/* Compute freq_drift due to PLL and FLL contributions.