fc47fcefb
Denys Vlasenko
2016-02-10
Subject
ntpd: step when |offset| > 1 sec, not 0.125 sec
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networking/ntpd.c+36 -18
| @@ -112,7 +112,7 @@ | |
| * | |
| * Made some changes to speed up re-syncing after our clock goes bad | |
| * (tested with suspending my laptop): | |
| - | * - if largish offset (>= STEP_THRESHOLD * 8 == 1 sec) is seen |
| + | * - if largish offset (>= STEP_THRESHOLD == 1 sec) is seen |
| * from a peer, schedule next query for this peer soon | |
| * without drastically lowering poll interval for everybody. | |
| * This makes us collect enough data for step much faster: | |
| @@ -131,11 +131,14 @@ | |
| #define RESPONSE_INTERVAL 16 /* wait for reply up to N secs */ | |
| /* Step threshold (sec). std ntpd uses 0.128. | |
| + | */ |
| + | #define STEP_THRESHOLD 1 |
| + | /* Slew threshold (sec): adjtimex() won't accept offsets larger than this. |
| * Using exact power of 2 (1/8) results in smaller code | |
| */ | |
| - | #define STEP_THRESHOLD 0.125 |
| + | #define SLEW_THRESHOLD 0.125 |
| /* Stepout threshold (sec). std ntpd uses 900 (11 mins (!)) */ | |
| - | #define WATCH_THRESHOLD 128 |
| + | #define WATCH_THRESHOLD 128 |
| /* NB: set WATCH_THRESHOLD to ~60 when debugging to save time) */ | |
| //UNUSED: #define PANIC_THRESHOLD 1000 /* panic threshold (sec) */ | |
| @@ -143,7 +146,7 @@ | |
| * If we got |offset| > BIGOFF from a peer, cap next query interval | |
| * for this peer by this many seconds: | |
| */ | |
| - | #define BIGOFF (STEP_THRESHOLD * 8) |
| + | #define BIGOFF STEP_THRESHOLD |
| #define BIGOFF_INTERVAL (1 << 7) /* 128 s */ | |
| #define FREQ_TOLERANCE 0.000015 /* frequency tolerance (15 PPM) */ | |
| @@ -157,10 +160,10 @@ | |
| #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 |
| + | * With SLEW_THRESHOLD = 0.125, it means we try to sync more aggressively |
| * if offset increases over ~0.04 sec | |
| */ | |
| - | //#define POLLDOWN_OFFSET (STEP_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) */ | |
| @@ -720,7 +723,7 @@ static void | |
| reset_peer_stats(peer_t *p, double offset) | |
| { | |
| int i; | |
| - | bool small_ofs = fabs(offset) < 16 * STEP_THRESHOLD; |
| + | bool small_ofs = fabs(offset) < STEP_THRESHOLD; |
| /* Used to set p->filter_datapoint[i].d_dispersion = MAXDISP | |
| * and clear reachable bits, but this proved to be too agressive: | |
| @@ -771,7 +774,7 @@ add_peers(const char *s) | |
| p->p_fd = -1; | |
| p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3); | |
| p->next_action_time = G.cur_time; /* = set_next(p, 0); */ | |
| - | reset_peer_stats(p, 16 * STEP_THRESHOLD); |
| + | reset_peer_stats(p, STEP_THRESHOLD); |
| llist_add_to(&G.ntp_peers, p); | |
| G.peer_cnt++; | |
| @@ -1638,14 +1641,7 @@ 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 = (offset * 1000000); /* usec */ |
| - | tmx.status = STA_PLL; |
| - | if (G.ntp_status & LI_PLUSSEC) |
| - | tmx.status |= STA_INS; |
| - | if (G.ntp_status & LI_MINUSSEC) |
| - | tmx.status |= STA_DEL; |
| - | |
| - | tmx.constant = (int)G.poll_exp - 4 > 0 ? (int)G.poll_exp - 4 : 0; |
| + | tmx.constant = (int)G.poll_exp - 4; |
| /* EXPERIMENTAL. | |
| * The below if statement should be unnecessary, but... | |
| * It looks like Linux kernel's PLL is far too gentle in changing | |
| @@ -1656,8 +1652,27 @@ update_local_clock(peer_t *p) | |
| * To be on a safe side, let's do it only if offset is significantly | |
| * larger than jitter. | |
| */ | |
| - | if (tmx.constant > 0 && G.offset_to_jitter_ratio >= TIMECONST_HACK_GATE) |
| + | if (G.offset_to_jitter_ratio >= TIMECONST_HACK_GATE) |
| tmx.constant--; | |
| + | tmx.offset = (long)(offset * 1000000); /* usec */ |
| + | if (SLEW_THRESHOLD < STEP_THRESHOLD) { |
| + | if (tmx.offset > (long)(SLEW_THRESHOLD * 1000000)) { |
| + | tmx.offset = (long)(SLEW_THRESHOLD * 1000000); |
| + | tmx.constant--; |
| + | } |
| + | if (tmx.offset < -(long)(SLEW_THRESHOLD * 1000000)) { |
| + | tmx.offset = -(long)(SLEW_THRESHOLD * 1000000); |
| + | tmx.constant--; |
| + | } |
| + | } |
| + | if (tmx.constant < 0) |
| + | tmx.constant = 0; |
| + | |
| + | tmx.status = STA_PLL; |
| + | if (G.ntp_status & LI_PLUSSEC) |
| + | tmx.status |= STA_INS; |
| + | if (G.ntp_status & LI_MINUSSEC) |
| + | tmx.status |= STA_DEL; |
| //tmx.esterror = (uint32_t)(clock_jitter * 1e6); | |
| //tmx.maxerror = (uint32_t)((sys_rootdelay / 2 + sys_rootdisp) * 1e6); | |
| @@ -1931,6 +1946,9 @@ recv_and_process_peer_pkt(peer_t *p) | |
| increase_interval: | |
| adjust_poll(MINPOLL); | |
| } else { | |
| + | VERB3 if (rc > 0) |
| + | bb_error_msg("want smaller poll interval: offset/jitter ratio > %u", |
| + | POLLADJ_GATE); |
| adjust_poll(-G.poll_exp * 2); | |
| } | |
| } | |
| @@ -1939,7 +1957,7 @@ recv_and_process_peer_pkt(peer_t *p) | |
| pick_normal_interval: | |
| interval = poll_interval(INT_MAX); | |
| if (fabs(offset) >= BIGOFF && interval > BIGOFF_INTERVAL) { | |
| - | /* If we are synced, offsets are less than STEP_THRESHOLD, |
| + | /* If we are synced, offsets are less than SLEW_THRESHOLD, |
| * or at the very least not much larger than it. | |
| * Now we see a largish one. | |
| * Either this peer is feeling bad, or packet got corrupted, | |