From 448fdcc17df39ac90c59d0588ccaf9ee0400eb7e Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Sun, 11 Mar 2018 17:08:02 +0100 Subject: ntpd: choose initial FREQHOLD_cnt dynamically function old new delta update_local_clock 834 858 +24 Signed-off-by: Denys Vlasenko --- networking/ntpd.c | 66 +++++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 54 insertions(+), 12 deletions(-) (limited to 'networking/ntpd.c') diff --git a/networking/ntpd.c b/networking/ntpd.c index 2754170c0..8205ab271 100644 --- a/networking/ntpd.c +++ b/networking/ntpd.c @@ -1715,9 +1715,19 @@ update_local_clock(peer_t *p) tmx.freq = G.discipline_freq_drift * 65536e6; #endif 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; if (G.FREQHOLD_cnt != 0) { - G.FREQHOLD_cnt--; /* man adjtimex on STA_FREQHOLD: * "Normally adjustments made via ADJ_OFFSET result in dampened * 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, * 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: offset:+0.485133 delay:0.157762 jitter:0.209310 clock drift:-1.393ppm tc:4 +//15:17:57.719 update from: offset:+0.483825 delay:0.158070 jitter:0.181159 clock drift:-1.393ppm tc:4 +//15:17:59.925 update from: offset:+0.479504 delay:0.158147 jitter:0.156657 clock drift:-1.393ppm tc:4 +//15:18:33.322 update from: offset:+0.428119 delay:0.158317 jitter:0.138071 clock drift:-1.393ppm tc:4 +//15:19:06.718 update from: offset:+0.376932 delay:0.158276 jitter:0.122075 clock drift:-1.393ppm tc:4 +//15:19:39.114 update from: offset:+0.327022 delay:0.158384 jitter:0.108538 clock drift:-1.393ppm tc:4 +//15:20:12.715 update from: offset:+0.275596 delay:0.158297 jitter:0.097292 clock drift:-1.393ppm tc:4 +//15:20:45.111 update from: 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: offset:+0.175910 delay:0.158314 jitter:0.076683 clock drift:-1.393ppm tc:4 +//15:21:19.774 update from: offset:+0.171784 delay:0.158401 jitter:0.066436 clock drift:-1.393ppm tc:4 +//15:21:22.140 update from: offset:+0.171660 delay:0.158592 jitter:0.057536 clock drift:-1.393ppm tc:4 +//15:21:22.140 update from: offset:+0.167126 delay:0.158507 jitter:0.049792 clock drift:-1.393ppm tc:4 +//15:21:55.696 update from: offset:+0.115223 delay:0.158277 jitter:0.050240 clock drift:-1.393ppm tc:4 +//15:22:29.093 update from: offset:+0.068051 delay:0.158243 jitter:0.049405 clock drift:-1.393ppm tc:5 +//15:23:02.490 update from: offset:+0.051632 delay:0.158215 jitter:0.043545 clock drift:-1.393ppm tc:5 +//15:23:34.726 update from: 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: offset:+0.030968 delay:0.158190 jitter:0.033306 clock drift:+2.387ppm tc:5 +//15:24:40.357 update from: offset:+0.023648 delay:0.158211 jitter:0.029072 clock drift:+5.454ppm tc:5 +//15:25:13.774 update from: offset:+0.018068 delay:0.157660 jitter:0.025288 clock drift:+7.728ppm tc:5 +//15:26:19.173 update from: offset:+0.010057 delay:0.157969 jitter:0.022255 clock drift:+8.361ppm tc:6 +//15:27:26.602 update from: offset:+0.006737 delay:0.158103 jitter:0.019316 clock drift:+8.792ppm tc:6 +//15:28:33.030 update from: offset:+0.004513 delay:0.158294 jitter:0.016765 clock drift:+9.080ppm tc:6 +//15:29:40.617 update from: offset:+0.002787 delay:0.157745 jitter:0.014543 clock drift:+9.258ppm tc:6 +//15:30:47.045 update from: offset:+0.001324 delay:0.157709 jitter:0.012594 clock drift:+9.342ppm tc:6 +//15:31:53.473 update from: offset:+0.000007 delay:0.158142 jitter:0.010922 clock drift:+9.343ppm tc:6 +//15:32:58.902 update from: 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; } if (G.ntp_status & LI_PLUSSEC) @@ -1753,16 +1805,6 @@ update_local_clock(peer_t *p) if (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.maxerror = (uint32_t)((sys_rootdelay / 2 + sys_rootdisp) * 1e6); rc = adjtimex(&tmx); @@ -2248,7 +2290,7 @@ static NOINLINE void ntp_init(char **argv) if (BURSTPOLL != 0) 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.FREQHOLD_cnt = 8; + G.FREQHOLD_cnt = -1; /* Parse options */ peers = NULL; -- cgit v1.2.3