emo/busybox
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

ntpd: choose initial FREQHOLD_cnt dynamically

Browse Source 
function                                             old     new   delta
update_local_clock                                   834     858     +24

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-03-11 17:08:02 +01:00
parent 3d306bffc5
commit 448fdcc17d
1 changed files with 54 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

66
networking/ntpd.c
View File

@ -1715,9 +1715,19 @@ update_local_clock(peer_t *p)
tmx.freq = G.discipline_freq_drift * 65536e6; tmx.freq = G.discipline_freq_drift * 65536e6;
#endif #endif
tmx.modes = ADJ_OFFSET | ADJ_STATUS | ADJ_TIMECONST;// | ADJ_MAXERROR | ADJ_ESTERROR; tmx.modes = ADJ_OFFSET | ADJ_STATUS | ADJ_TIMECONST;// | ADJ_MAXERROR | ADJ_ESTERROR;
tmx.offset = (long)(offset * 1000000); /* usec */
if (SLEW_THRESHOLD < STEP_THRESHOLD) {
if (tmx.offset > (long)(SLEW_THRESHOLD * 1000000)) {
tmx.offset = (long)(SLEW_THRESHOLD * 1000000);
}
if (tmx.offset < -(long)(SLEW_THRESHOLD * 1000000)) {
tmx.offset = -(long)(SLEW_THRESHOLD * 1000000);
}
}
tmx.status = STA_PLL; tmx.status = STA_PLL;
if (G.FREQHOLD_cnt != 0) { if (G.FREQHOLD_cnt != 0) {
G.FREQHOLD_cnt--;
/* man adjtimex on STA_FREQHOLD: /* man adjtimex on STA_FREQHOLD:
* "Normally adjustments made via ADJ_OFFSET result in dampened * "Normally adjustments made via ADJ_OFFSET result in dampened
* frequency adjustments also being made. * frequency adjustments also being made.
@ -1730,6 +1740,48 @@ update_local_clock(peer_t *p)
* If ntpd was restarted due to e.g. switch to another network, * If ntpd was restarted due to e.g. switch to another network,
* this destroys already well-established tmx.freq value. * this destroys already well-established tmx.freq value.
*/ */
if (G.FREQHOLD_cnt < 0) {
/* Initialize it */
// Example: a laptop whose clock runs slower when hibernated,
// after wake up it still has good tmx.freq, but accumulated ~0.5 sec offset:
// Run with code where initial G.FREQHOLD_cnt was always 8:
//15:17:52.947 no valid datapoints, no peer selected
//15:17:56.515 update from:<IP> offset:+0.485133 delay:0.157762 jitter:0.209310 clock drift:-1.393ppm tc:4
//15:17:57.719 update from:<IP> offset:+0.483825 delay:0.158070 jitter:0.181159 clock drift:-1.393ppm tc:4
//15:17:59.925 update from:<IP> offset:+0.479504 delay:0.158147 jitter:0.156657 clock drift:-1.393ppm tc:4
//15:18:33.322 update from:<IP> offset:+0.428119 delay:0.158317 jitter:0.138071 clock drift:-1.393ppm tc:4
//15:19:06.718 update from:<IP> offset:+0.376932 delay:0.158276 jitter:0.122075 clock drift:-1.393ppm tc:4
//15:19:39.114 update from:<IP> offset:+0.327022 delay:0.158384 jitter:0.108538 clock drift:-1.393ppm tc:4
//15:20:12.715 update from:<IP> offset:+0.275596 delay:0.158297 jitter:0.097292 clock drift:-1.393ppm tc:4
//15:20:45.111 update from:<IP> offset:+0.225715 delay:0.158271 jitter:0.087841 clock drift:-1.393ppm tc:4
// If allwed to continue, it would start increasing tmx.freq now.
// Instead, it was ^Ced, and started anew:
//15:21:15.043 no valid datapoints, no peer selected
//15:21:17.408 update from:<IP> offset:+0.175910 delay:0.158314 jitter:0.076683 clock drift:-1.393ppm tc:4
//15:21:19.774 update from:<IP> offset:+0.171784 delay:0.158401 jitter:0.066436 clock drift:-1.393ppm tc:4
//15:21:22.140 update from:<IP> offset:+0.171660 delay:0.158592 jitter:0.057536 clock drift:-1.393ppm tc:4
//15:21:22.140 update from:<IP> offset:+0.167126 delay:0.158507 jitter:0.049792 clock drift:-1.393ppm tc:4
//15:21:55.696 update from:<IP> offset:+0.115223 delay:0.158277 jitter:0.050240 clock drift:-1.393ppm tc:4
//15:22:29.093 update from:<IP> offset:+0.068051 delay:0.158243 jitter:0.049405 clock drift:-1.393ppm tc:5
//15:23:02.490 update from:<IP> offset:+0.051632 delay:0.158215 jitter:0.043545 clock drift:-1.393ppm tc:5
//15:23:34.726 update from:<IP> offset:+0.039984 delay:0.158157 jitter:0.038106 clock drift:-1.393ppm tc:5
// STA_FREQHOLD no longer set, started increasing tmx.freq now:
//15:24:06.961 update from:<IP> offset:+0.030968 delay:0.158190 jitter:0.033306 clock drift:+2.387ppm tc:5
//15:24:40.357 update from:<IP> offset:+0.023648 delay:0.158211 jitter:0.029072 clock drift:+5.454ppm tc:5
//15:25:13.774 update from:<IP> offset:+0.018068 delay:0.157660 jitter:0.025288 clock drift:+7.728ppm tc:5
//15:26:19.173 update from:<IP> offset:+0.010057 delay:0.157969 jitter:0.022255 clock drift:+8.361ppm tc:6
//15:27:26.602 update from:<IP> offset:+0.006737 delay:0.158103 jitter:0.019316 clock drift:+8.792ppm tc:6
//15:28:33.030 update from:<IP> offset:+0.004513 delay:0.158294 jitter:0.016765 clock drift:+9.080ppm tc:6
//15:29:40.617 update from:<IP> offset:+0.002787 delay:0.157745 jitter:0.014543 clock drift:+9.258ppm tc:6
//15:30:47.045 update from:<IP> offset:+0.001324 delay:0.157709 jitter:0.012594 clock drift:+9.342ppm tc:6
//15:31:53.473 update from:<IP> offset:+0.000007 delay:0.158142 jitter:0.010922 clock drift:+9.343ppm tc:6
//15:32:58.902 update from:<IP> offset:-0.000728 delay:0.158222 jitter:0.009454 clock drift:+9.298ppm tc:6
/*
* This expression would choose 15 in the above example.
*/
G.FREQHOLD_cnt = 8 + ((unsigned)(abs(tmx.offset)) >> 16);
}
G.FREQHOLD_cnt--;
tmx.status |= STA_FREQHOLD; tmx.status |= STA_FREQHOLD;
} }
if (G.ntp_status & LI_PLUSSEC) if (G.ntp_status & LI_PLUSSEC)
@ -1753,16 +1805,6 @@ update_local_clock(peer_t *p)
if (tmx.constant < 0) if (tmx.constant < 0)
tmx.constant = 0; tmx.constant = 0;
tmx.offset = (long)(offset * 1000000); /* usec */
if (SLEW_THRESHOLD < STEP_THRESHOLD) {
if (tmx.offset > (long)(SLEW_THRESHOLD * 1000000)) {
tmx.offset = (long)(SLEW_THRESHOLD * 1000000);
}
if (tmx.offset < -(long)(SLEW_THRESHOLD * 1000000)) {
tmx.offset = -(long)(SLEW_THRESHOLD * 1000000);
}
}
//tmx.esterror = (uint32_t)(clock_jitter * 1e6); //tmx.esterror = (uint32_t)(clock_jitter * 1e6);
//tmx.maxerror = (uint32_t)((sys_rootdelay / 2 + sys_rootdisp) * 1e6); //tmx.maxerror = (uint32_t)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
rc = adjtimex(&tmx); rc = adjtimex(&tmx);
@ -2248,7 +2290,7 @@ static NOINLINE void ntp_init(char **argv)
if (BURSTPOLL != 0) if (BURSTPOLL != 0)
G.poll_exp = BURSTPOLL; /* speeds up initial sync */ G.poll_exp = BURSTPOLL; /* speeds up initial sync */
G.last_script_run = G.reftime = G.last_update_recv_time = gettime1900d(); /* sets G.cur_time too */ G.last_script_run = G.reftime = G.last_update_recv_time = gettime1900d(); /* sets G.cur_time too */
G.FREQHOLD_cnt = 8; G.FREQHOLD_cnt = -1;
/* Parse options */ /* Parse options */
peers = NULL; peers = NULL;