diff options
Diffstat (limited to 'networking')
| -rw-r--r-- | networking/ntpd.c | 32 |
1 files changed, 9 insertions, 23 deletions
diff --git a/networking/ntpd.c b/networking/ntpd.c index caf5cc299..0f350fa6f 100644 --- a/networking/ntpd.c +++ b/networking/ntpd.c @@ -127,24 +127,15 @@ */ #define MAX_VERBOSE 3 - /* High-level description of the algorithm: * * We start running with very small poll_exp, BURSTPOLL, * in order to quickly accumulate INITIAL_SAMPLES datapoints * for each peer. Then, time is stepped if the offset is larger - * than STEP_THRESHOLD, otherwise it isn't; anyway, we enlarge - * poll_exp to MINPOLL and enter frequency measurement step: - * we collect new datapoints but ignore them for WATCH_THRESHOLD - * 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) + * than STEP_THRESHOLD, otherwise it isn't stepped. * - * After this, we enter "steady state": we collect a datapoint, - * we select the best peer, if this datapoint is not a new one + * Then poll_exp is set to MINPOLL, and 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 * and collect another one; otherwise, use its offset to update * frequency drift, if offset is somewhat large, reduce poll_exp, @@ -189,13 +180,10 @@ // ^^^^ used to be 0.125. // Since Linux 2.6.26 (circa 2006), kernel accepts (-0.5s, +0.5s) range -/* Stepout threshold (sec). std ntpd uses 900 (11 mins (!)) */ -//UNUSED: #define WATCH_THRESHOLD 128 -/* NB: set WATCH_THRESHOLD to ~60 when debugging to save time) */ -//UNUSED: #define PANIC_THRESHOLD 1000 /* panic threshold (sec) */ -/* - * If we got |offset| > BIGOFF from a peer, cap next query interval +// #define PANIC_THRESHOLD 1000 /* panic threshold (sec) */ + +/* If we got |offset| > BIGOFF from a peer, cap next query interval * for this peer by this many seconds: */ #define BIGOFF STEP_THRESHOLD @@ -204,18 +192,16 @@ #define FREQ_TOLERANCE 0.000015 /* frequency tolerance (15 PPM) */ #define BURSTPOLL 0 /* initial poll */ #define MINPOLL 5 /* minimum poll interval. std ntpd uses 6 (6: 64 sec) */ -/* - * If offset > discipline_jitter * POLLADJ_GATE, and poll interval is > 2^BIGPOLL, +/* If offset > discipline_jitter * POLLADJ_GATE, and poll interval is > 2^BIGPOLL, * then it is decreased _at once_. (If <= 2^BIGPOLL, it will be decreased _eventually_). */ #define BIGPOLL 9 /* 2^9 sec ~= 8.5 min */ #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. +/* Actively lower poll when we see such big offsets. * With SLEW_THRESHOLD = 0.125, it means we try to sync more aggressively * if offset increases over ~0.04 sec */ -//#define POLLDOWN_OFFSET (SLEW_THRESHOLD / 3) +// #define POLLDOWN_OFFSET (SLEW_THRESHOLD / 3) #define MINDISP 0.01 /* minimum dispersion (sec) */ #define MAXDISP 16 /* maximum dispersion (sec) */ #define MAXSTRAT 16 /* maximum stratum (infinity metric) */ |