do not log tiny local clock drifts; w/ help from Joerg Sonnenberger <joerg@britannica.bec.de>; henning@ ok

src/usr.sbin/ntpd/ntpd.8

@@ -1,4 +1,4 @@
-.\" $OpenBSD: ntpd.8,v 1.10 2004/11/02 18:00:38 henning Exp $
+.\" $OpenBSD: ntpd.8,v 1.11 2004/12/06 20:57:17 mickey Exp $
 .\"
 .\" Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
 .\"
@@ -41,6 +41,16 @@ as described in RFC 1305.
 uses the
 .Xr adjtime 2
 system call to correct the local system time without causing time jumps.
+Adjustments larger then 128ms are logged using
+.Xr syslog 3 .
+The threshold value is chosen to avoid local clock drift thrash the log files.
+Should
+.Nm
+be started with
+.Fl d
+option all calls to
+.Xr adjtime 2
+will be logged.
 .Pp
 .Nm
 is usually started at boot time, and can be enabled by

src/usr.sbin/ntpd/ntpd.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntpd.c,v 1.24 2004/11/10 11:27:54 henning Exp $ */
+/*	$OpenBSD: ntpd.c,v 1.25 2004/12/06 20:57:17 mickey Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -306,8 +306,11 @@ ntpd_adjtime(double d)
 {
 	struct timeval	tv;
 
+	if (d >= (double)LOG_NEGLIGEE / 1000)
+		log_info("adjusting local clock by %fs", d);
+	else
+		log_debug("adjusting local clock by %fs", d);
 	d_to_tv(d, &tv);
-	log_info("adjusting local clock by %fs", d);
 	if (adjtime(&tv, NULL) == -1)
 		log_warn("adjtime failed");
 }

src/usr.sbin/ntpd/ntpd.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntpd.h,v 1.45 2004/12/06 16:52:33 mickey Exp $ */
+/*	$OpenBSD: ntpd.h,v 1.46 2004/12/06 20:57:17 mickey Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -52,6 +52,7 @@
 #define	QUERYTIME_MAX		15	/* single query might take n secs max */
 #define	OFFSET_ARRAY_SIZE	8
 #define	SETTIME_MIN_OFFSET	180	/* min offset for settime at start */
+#define	LOG_NEGLIGEE		128	/* negligible drift to not log (ms) */
 
 enum client_state {
 	STATE_NONE,