[git commit] ntpd: calculate offset to jitter ratio before updating jitter

[Denys Vlasenko]

commit: http://git.busybox.net/busybox/commit/?id=760d035699c4a878f9109544c1d35ea0d5f6b76c
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master

The offset to jitter ratio is now calculated before updating
jitter to make the test more sensitive.

function                                             old     new   delta
ntp_init                                             460     474     +14
update_local_clock                                   752     764     +12
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 26/0)               Total: 26 bytes

Signed-off-by: Miroslav Lichvar <mlichvar at redhat.com>
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 networking/ntpd.c |   12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/networking/ntpd.c b/networking/ntpd.c
index 838a367..2d4f076 100644
--- a/networking/ntpd.c
+++ b/networking/ntpd.c
@@ -1488,12 +1488,19 @@ update_local_clock(peer_t *p)
 
 	} else { /* abs_offset <= STEP_THRESHOLD */
 
+		/* The ratio is calculated before jitter is updated to make
+		 * poll adjust code more sensitive to large offsets.
+		 */
+		G.offset_to_jitter_ratio = abs_offset / G.discipline_jitter;
+
 		/* Compute the clock jitter as the RMS of exponentially
 		 * weighted offset differences. Used by the poll adjust code.
 		 */
 		etemp = SQUARE(G.discipline_jitter);
 		dtemp = SQUARE(offset - G.last_update_offset);
 		G.discipline_jitter = SQRT(etemp + (dtemp - etemp) / AVG);
+		if (G.discipline_jitter < G_precision_sec)
+			G.discipline_jitter = G_precision_sec;
 
 		switch (G.discipline_state) {
 		case STATE_NSET:
@@ -1570,10 +1577,6 @@ update_local_clock(peer_t *p)
 		}
 	}
 
-	if (G.discipline_jitter < G_precision_sec)
-		G.discipline_jitter = G_precision_sec;
-	G.offset_to_jitter_ratio = abs_offset / G.discipline_jitter;
-
 	G.reftime = G.cur_time;
 	G.ntp_status = p->lastpkt_status;
 	G.refid = p->lastpkt_refid;
@@ -2111,6 +2114,7 @@ static NOINLINE void ntp_init(char **argv)
 		bb_error_msg_and_die(bb_msg_you_must_be_root);
 
 	/* Set some globals */
+	G.discipline_jitter = G_precision_sec;
 	G.stratum = MAXSTRAT;
 	if (BURSTPOLL != 0)
 		G.poll_exp = BURSTPOLL; /* speeds up initial sync */