ntpd: calculate offset to jitter ratio before updating jitter

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@redhat.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/networking/ntpd.c b/networking/ntpd.c
index 838a367fe236502993210057c6244fb127ae4617..2d4f076d99915a64aaf8418c3c4f5f40990ad3c0 100644 (file)
--- 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 */