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authorDenys Vlasenko <vda.linux@googlemail.com>2013-12-07 16:29:03 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2013-12-07 16:29:03 (GMT)
commit777be10ebebb4afdaf057a5abe094c86eb6d8a2c (patch)
tree71ac6b6f7d6354c3ae464a9213aa3e44f69f866c
parent6c46eed6e935db43dedbff1d026e4cf68f0bc67e (diff)
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ntpd: do not invalidate datapoints after step
Used to set p->filter_datapoint[i].d_dispersion = MAXDISP and clear reachable bits, but this proved to be too agressive: after step (tested with suspinding laptop for ~30 secs), this caused all previous data to be considered invalid, making us needing to collect full ~8 datapoins per peer after step in order to start trusting them. In turn, this was making poll interval decrease even after step was done. (Poll interval decreases already before step in this scenario, because we see large offsets and end up with no good peer to select). function old new delta reset_peer_stats 157 139 -18 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--networking/ntpd.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/networking/ntpd.c b/networking/ntpd.c
index f3a4177..fd2f24a 100644
--- a/networking/ntpd.c
+++ b/networking/ntpd.c
@@ -678,6 +678,18 @@ reset_peer_stats(peer_t *p, double offset)
int i;
bool small_ofs = fabs(offset) < 16 * STEP_THRESHOLD;
+ /* Used to set p->filter_datapoint[i].d_dispersion = MAXDISP
+ * and clear reachable bits, but this proved to be too agressive:
+ * after step (tested with suspinding laptop for ~30 secs),
+ * this caused all previous data to be considered invalid,
+ * making us needing to collect full ~8 datapoins per peer
+ * after step in order to start trusting them.
+ * In turn, this was making poll interval decrease even after
+ * step was done. (Poll interval decreases already before step
+ * in this scenario, because we see large offsets and end up with
+ * no good peer to select).
+ */
+
for (i = 0; i < NUM_DATAPOINTS; i++) {
if (small_ofs) {
p->filter_datapoint[i].d_recv_time += offset;
@@ -691,13 +703,13 @@ reset_peer_stats(peer_t *p, double offset)
} else {
p->filter_datapoint[i].d_recv_time = G.cur_time;
p->filter_datapoint[i].d_offset = 0;
- p->filter_datapoint[i].d_dispersion = MAXDISP;
+ /*p->filter_datapoint[i].d_dispersion = MAXDISP;*/
}
}
if (small_ofs) {
p->lastpkt_recv_time += offset;
} else {
- p->reachable_bits = 0;
+ /*p->reachable_bits = 0;*/
p->lastpkt_recv_time = G.cur_time;
}
filter_datapoints(p); /* recalc p->filter_xxx */