From e8ce285395d801e551811ed3eb9df25a6d46df0e Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Sat, 3 Mar 2012 12:15:46 +0100 Subject: [PATCH] ntpd: avoid printing messages between send and recv. good for fast networks function old new delta ntpd_main 887 929 +42 Signed-off-by: Denys Vlasenko --- networking/ntpd.c | 37 ++++++++++++++++++++++++++++++------- 1 file changed, 30 insertions(+), 7 deletions(-) diff --git a/networking/ntpd.c b/networking/ntpd.c index e86f72f83..938c7f040 100644 --- a/networking/ntpd.c +++ b/networking/ntpd.c @@ -107,7 +107,10 @@ #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) */ -#define BIGPOLL 10 /* drop to lower poll at any trouble (10: 17 min) */ +/* 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 10 /* 2^10 sec ~= 17 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. * With STEP_THRESHOLD = 0.125, it means we try to sync more aggressively @@ -124,13 +127,13 @@ /* Poll-adjust threshold. * When we see that offset is small enough compared to discipline jitter, - * we grow a counter: += MINPOLL. When it goes over POLLADJ_LIMIT, + * we grow a counter: += MINPOLL. When counter goes over POLLADJ_LIMIT, * we poll_exp++. If offset isn't small, counter -= poll_exp*2, - * and when it goes below -POLLADJ_LIMIT, we poll_exp-- - * (bumped from 30 to 40 since otherwise I often see poll_exp going *2* steps down) + * and when it goes below -POLLADJ_LIMIT, we poll_exp--. + * (Bumped from 30 to 40 since otherwise I often see poll_exp going *2* steps down) */ #define POLLADJ_LIMIT 40 -/* If offset < POLLADJ_GATE * discipline_jitter, then we can increase +/* If offset < discipline_jitter * POLLADJ_GATE, then we decide to increase * poll interval (we think we can't improve timekeeping * by staying at smaller poll). */ @@ -732,6 +735,12 @@ send_query_to_peer(peer_t *p) free(local_lsa); } + /* Emit message _before_ attempted send. Think of a very short + * roundtrip networks: we need to go back to recv loop ASAP, + * to reduce delay. Printing messages after send works against that. + */ + VERB1 bb_error_msg("sending query to %s", p->p_dotted); + /* * Send out a random 64-bit number as our transmit time. The NTP * server will copy said number into the originate field on the @@ -759,7 +768,6 @@ send_query_to_peer(peer_t *p) } p->reachable_bits <<= 1; - VERB1 bb_error_msg("sent query to %s", p->p_dotted); set_next(p, RESPONSE_INTERVAL); } @@ -2077,8 +2085,23 @@ int ntpd_main(int argc UNUSED_PARAM, char **argv) timeout++; /* (nextaction - G.cur_time) rounds down, compensating */ /* Here we may block */ - VERB2 bb_error_msg("poll %us, sockets:%u, poll interval:%us", timeout, i, 1 << G.poll_exp); + VERB2 { + if (i > ENABLE_FEATURE_NTPD_SERVER) { + /* We wait for at least one reply. + * Poll for it, without wasting time for message. + * Since replies often come under 1 second, this also + * reduces clutter in logs. + */ + nfds = poll(pfd, i, 1000); + if (nfds != 0) + goto did_poll; + if (--timeout <= 0) + goto did_poll; + } + bb_error_msg("poll %us, sockets:%u, poll interval:%us", timeout, i, 1 << G.poll_exp); + } nfds = poll(pfd, i, timeout * 1000); + did_poll: gettime1900d(); /* sets G.cur_time */ if (nfds <= 0) { if (G.script_name && G.cur_time - G.last_script_run > 11*60) {