diff options
| -rw-r--r-- | networking/ntpd.c | 69 |
1 files changed, 45 insertions, 24 deletions
diff --git a/networking/ntpd.c b/networking/ntpd.c index e52d20c01..b2cd0a3c0 100644 --- a/networking/ntpd.c +++ b/networking/ntpd.c @@ -57,6 +57,10 @@ * seconds. After WATCH_THRESHOLD seconds we look at accumulated * offset and estimate frequency drift. * + * (frequency measurement step seems to not be strictly needed, + * it is conditionally disabled with USING_INITIAL_FREQ_ESTIMATION + * define set to 0) + * * After this, we enter "steady state": we collect a datapoint, * we select the best peer, if this datapoint is not a new one * (IOW: if this datapoint isn't for selected peer), sleep @@ -76,21 +80,27 @@ #define INITIAL_SAMLPES 4 /* how many samples do we want for init */ /* Clock discipline parameters and constants */ -#define STEP_THRESHOLD 0.128 /* step threshold (s) */ -#define WATCH_THRESHOLD 150 /* stepout threshold (s). std ntpd uses 900 (11 mins (!)) */ + +/* Step threshold (sec). std ntpd uses 0.128. + * Using exact power of 2 (1/8) results in smaller code */ +#define STEP_THRESHOLD 0.125 +#define WATCH_THRESHOLD 128 /* stepout threshold (sec). std ntpd uses 900 (11 mins (!)) */ /* NB: set WATCH_THRESHOLD to ~60 when debugging to save time) */ -//UNUSED: #define PANIC_THRESHOLD 1000 /* panic threshold (s) */ +//UNUSED: #define PANIC_THRESHOLD 1000 /* panic threshold (sec) */ #define FREQ_TOLERANCE 0.000015 /* frequency tolerance (15 PPM) */ #define BURSTPOLL 0 /* initial poll */ -#define MINPOLL 4 /* minimum poll interval (6: 64 s) */ +#define MINPOLL 5 /* minimum poll interval. std ntpd uses 6 (6: 64 sec) */ #define BIGPOLL 10 /* drop to lower poll at any trouble (10: 17 min) */ -#define MAXPOLL 12 /* maximum poll interval (12: 1.1h, 17: 36.4h) (was 17) */ -#define POLLDOWN_OFFSET (STEP_THRESHOLD / 3) /* actively lower poll when we see such big offsets */ -#define MINDISP 0.01 /* minimum dispersion (s) */ -#define MAXDISP 16 /* maximum dispersion (s) */ +#define MAXPOLL 12 /* maximum poll interval (12: 1.1h, 17: 36.4h). std ntpd uses 17 */ +/* Actively lower poll when we see such big offsets. + * With STEP_THRESHOLD = 0.125, it means we try to sync more aggressively + * if offset increases over 0.03 sec */ +#define POLLDOWN_OFFSET (STEP_THRESHOLD / 4) +#define MINDISP 0.01 /* minimum dispersion (sec) */ +#define MAXDISP 16 /* maximum dispersion (sec) */ #define MAXSTRAT 16 /* maximum stratum (infinity metric) */ -#define MAXDIST 1 /* distance threshold (s) */ +#define MAXDIST 1 /* distance threshold (sec) */ #define MIN_SELECTED 1 /* minimum intersection survivors */ #define MIN_CLUSTERED 3 /* minimum cluster survivors */ @@ -109,7 +119,7 @@ * by staying at smaller poll). */ #define POLLADJ_GATE 4 -/* Compromise Allan intercept (s). doc uses 1500, std ntpd uses 512 */ +/* Compromise Allan intercept (sec). doc uses 1500, std ntpd uses 512 */ #define ALLAN 512 /* PLL loop gain */ #define PLL 65536 @@ -214,6 +224,9 @@ typedef struct { } peer_t; +#define USING_KERNEL_PLL_LOOP 1 +#define USING_INITIAL_FREQ_ESTIMATION 0 + enum { OPT_n = (1 << 0), OPT_q = (1 << 1), @@ -284,6 +297,11 @@ struct globals { smallint adjtimex_was_done; smallint initial_poll_complete; +#define STATE_NSET 0 /* initial state, "nothing is set" */ +//#define STATE_FSET 1 /* frequency set from file */ +#define STATE_SPIK 2 /* spike detected */ +//#define STATE_FREQ 3 /* initial frequency */ +#define STATE_SYNC 4 /* clock synchronized (normal operation) */ uint8_t discipline_state; // doc calls it c.state uint8_t poll_exp; // s.poll int polladj_count; // c.count @@ -292,7 +310,6 @@ struct globals { double last_update_recv_time; // s.t double discipline_jitter; // c.jitter //TODO: add s.jitter - grep for it here and see clock_combine() in doc -#define USING_KERNEL_PLL_LOOP 1 #if !USING_KERNEL_PLL_LOOP double discipline_freq_drift; // c.freq //TODO: conditionally calculate wander? it's used only for logging @@ -581,8 +598,10 @@ static void reset_peer_stats(peer_t *p, double offset) { int i; + bool small_ofs = fabs(offset) < 16 * STEP_THRESHOLD; + for (i = 0; i < NUM_DATAPOINTS; i++) { - if (offset < 16 * STEP_THRESHOLD) { + if (small_ofs) { p->filter_datapoint[i].d_recv_time -= offset; if (p->filter_datapoint[i].d_offset != 0) { p->filter_datapoint[i].d_offset -= offset; @@ -593,7 +612,7 @@ reset_peer_stats(peer_t *p, double offset) p->filter_datapoint[i].d_dispersion = MAXDISP; } } - if (offset < 16 * STEP_THRESHOLD) { + if (small_ofs) { p->lastpkt_recv_time -= offset; } else { p->reachable_bits = 0; @@ -1105,12 +1124,6 @@ set_new_values(int disc_state, double offset, double recv_time) G.last_update_offset = offset; G.last_update_recv_time = recv_time; } -/* Clock state definitions */ -#define STATE_NSET 0 /* initial state, "nothing is set" */ -#define STATE_FSET 1 /* frequency set from file */ -#define STATE_SPIK 2 /* spike detected */ -#define STATE_FREQ 3 /* initial frequency */ -#define STATE_SYNC 4 /* clock synchronized (normal operation) */ /* Return: -1: decrease poll interval, 0: leave as is, 1: increase */ static NOINLINE int update_local_clock(peer_t *p) @@ -1156,6 +1169,7 @@ update_local_clock(peer_t *p) #if !USING_KERNEL_PLL_LOOP 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) { @@ -1163,10 +1177,11 @@ update_local_clock(peer_t *p) WATCH_THRESHOLD - since_last_update); return 0; /* "leave poll interval as is" */ } -#if !USING_KERNEL_PLL_LOOP +# if !USING_KERNEL_PLL_LOOP freq_drift = (offset - G.last_update_offset) / since_last_update; -#endif +# endif } +#endif /* There are two main regimes: when the * offset exceeds the step threshold and when it does not. @@ -1225,10 +1240,12 @@ update_local_clock(peer_t *p) run_script("step", 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 set_new_values(STATE_SYNC, /*offset:*/ 0, recv_time); } else { /* abs_offset <= STEP_THRESHOLD */ @@ -1255,11 +1272,15 @@ 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 VERB3 bb_error_msg("transitioning to FREQ, datapoint ignored"); return 0; /* "leave poll interval as is" */ @@ -1274,6 +1295,7 @@ update_local_clock(peer_t *p) 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. @@ -1281,6 +1303,7 @@ update_local_clock(peer_t *p) */ set_new_values(STATE_SYNC, offset, recv_time); break; +#endif default: #if !USING_KERNEL_PLL_LOOP @@ -1579,9 +1602,7 @@ recv_and_process_peer_pkt(peer_t *p) /* If drift is dangerously large, immediately * drop poll interval one step down. */ - if (q->filter_offset < -POLLDOWN_OFFSET - || q->filter_offset > POLLDOWN_OFFSET - ) { + if (fabs(q->filter_offset) >= POLLDOWN_OFFSET) { VERB3 bb_error_msg("offset:%f > POLLDOWN_OFFSET", q->filter_offset); goto poll_down; } |