query interval scaling, episode II

1) base the interval calculation on the offset from the last reply, not
   from the last peer update.
   Allows us to send more queries again faster when the local clock
   diverges too much
2) every time we form a peer update (for which we need 8 replies)
   check wether we have a ready peer update for all peers that are
   currently trusted, and if so, calculate the total offset and call
   adjtime().
   that means that adjtime is no longer called in fixed intervals
   but whenever we have enough data to reliably calculate the local
   clock offset.
   In practice, that means we call adjtime() less often, but with
   probably better data.
3) invalidate peer updates after beeing used. no point in re-using them
   - this resulted in calling adjtime() multiple times with the same
   offset, which doesn't make sense
tested by many

1 files changed, 13 insertions, 21 deletions

diff --git a/usr.sbin/ntpd/ntp.c b/usr.sbin/ntpd/ntp.c
index efeddd56a18..5326c28f5e5 100644
--- a/usr.sbin/ntpd/ntp.c
+++ b/usr.sbin/ntpd/ntp.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntp.c,v 1.24 2004/07/14 20:16:31 henning Exp $ */
+/*	$OpenBSD: ntp.c,v 1.25 2004/07/18 12:59:41 henning Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -34,10 +34,10 @@
 volatile sig_atomic_t	 ntp_quit = 0;
 struct imsgbuf		 ibuf_main;
 struct l_fixedpt	 ref_ts;
+struct ntpd_conf	*conf;
 
 void	ntp_sighdlr(int);
 int	ntp_dispatch_imsg(void);
-void	ntp_adjtime(struct ntpd_conf *);
 
 void
 ntp_sighdlr(int sig)
@@ -51,7 +51,7 @@ ntp_sighdlr(int sig)
 }
 
 pid_t
-ntp_main(int pipe_prnt[2], struct ntpd_conf *conf)
+ntp_main(int pipe_prnt[2], struct ntpd_conf *nconf)
 {
 	int			 nfds, i, j, idx_peers, timeout;
 	u_int			 pfd_elms = 0, idx2peer_elms = 0;
@@ -63,7 +63,7 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *conf)
 	struct listen_addr	*la;
 	struct ntp_peer		*p;
 	struct ntp_peer		**idx2peer = NULL;
-	time_t			 nextaction, next_adjtime;
+	time_t			 nextaction;
 	void			*newp;
 
 	switch (pid = fork()) {
@@ -88,6 +88,7 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *conf)
 
 	setproctitle("ntp engine");
 
+	conf = nconf;
 	setup_listeners(se, conf, &listener_cnt);
 
 	if (setgroups(1, &pw->pw_gid) ||
@@ -118,8 +119,6 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *conf)
 	TAILQ_FOREACH(p, &conf->ntp_peers, entry)
 		peer_cnt++;
 
-	next_adjtime = time(NULL) + INTERVAL_ADJTIME;
-
 	while (ntp_quit == 0) {
 		if (peer_cnt > idx2peer_elms ||
 		    peer_cnt + IDX2PEER_RESERVE < idx2peer_elms) {
@@ -152,7 +151,7 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *conf)
 
 		bzero(pfd, sizeof(struct pollfd) * pfd_elms);
 		bzero(idx2peer, sizeof(void *) * idx2peer_elms);
-		nextaction = next_adjtime;
+		nextaction = time(NULL) + 3600;
 		pfd[PFD_PIPE_MAIN].fd = ibuf_main.fd;
 		pfd[PFD_PIPE_MAIN].events = POLLIN;
 
@@ -193,11 +192,6 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *conf)
 			}
 		}
 
-		if (next_adjtime <= time(NULL)) {
-			next_adjtime = time(NULL) + INTERVAL_ADJTIME;
-			ntp_adjtime(conf);
-		}
-
 		if (ibuf_main.w.queued > 0)
 			pfd[PFD_PIPE_MAIN].events |= POLLOUT;
 
@@ -277,24 +271,19 @@ ntp_dispatch_imsg(void)
 }
 
 void
-ntp_adjtime(struct ntpd_conf *conf)
+ntp_adjtime(void)
 {
 	struct ntp_peer	*p;
 	double		 offset_median = 0;
 	int		 offset_cnt = 0;
 
 	TAILQ_FOREACH(p, &conf->ntp_peers, entry) {
-		if (!p->update.good)
-			continue;
-
-		if (p->update.rcvd + REPLY_MAXAGE < time(NULL)) {
-			p->update.good = 0;
-			continue;
-		}
-
 		if (p->trustlevel < TRUSTLEVEL_BADPEER)
 			continue;
 
+		if (!p->update.good)
+			return;
+
 		offset_median += p->update.offset;
 		offset_cnt++;
 	}
@@ -307,4 +296,7 @@ ntp_adjtime(struct ntpd_conf *conf)
 		conf->status.reftime = gettime();
 		conf->status.leap = LI_NOWARNING;		/* XXX */
 	}
+
+	TAILQ_FOREACH(p, &conf->ntp_peers, entry)
+		p->update.good = 0;
 }