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authorMiroslav Lichvar <mlichvar@redhat.com>2014-09-02 14:29:51 +0200
committerKay Sievers <kay@vrfy.org>2014-09-02 14:29:51 +0200
commite8206972be6a7ebeb198cd0d400bc7a94a6a5fc5 (patch)
treef50aa6e0670e32bddc0abb42c653c4bd04e48ff2 /src/timesync
parent665c6a9eab46b0b253af6566ca9fc70c866b3fcd (diff)
timesyncd: allow two missed replies before reselecting server
After receiving a reply from the server, allow two missed replies before switching to another server to avoid unnecessary clock hopping when packets are getting lost in the network.
Diffstat (limited to 'src/timesync')
-rw-r--r--src/timesync/timesyncd-manager.c27
-rw-r--r--src/timesync/timesyncd-manager.h1
2 files changed, 19 insertions, 9 deletions
diff --git a/src/timesync/timesyncd-manager.c b/src/timesync/timesyncd-manager.c
index 19a28f37e2..a66852d7d2 100644
--- a/src/timesync/timesyncd-manager.c
+++ b/src/timesync/timesyncd-manager.c
@@ -92,6 +92,9 @@
/* Maximum acceptable root distance in seconds. */
#define NTP_MAX_ROOT_DISTANCE 5.0
+/* Maximum number of missed replies before selecting another source. */
+#define NTP_MAX_MISSED_REPLIES 2
+
/*
* "NTP timestamps are represented as a 64-bit unsigned fixed-point number,
* in seconds relative to 0h on 1 January 1900."
@@ -206,15 +209,18 @@ static int manager_send_request(Manager *m) {
return manager_connect(m);
}
- r = sd_event_add_time(
- m->event,
- &m->event_timeout,
- clock_boottime_or_monotonic(),
- now(clock_boottime_or_monotonic()) + TIMEOUT_USEC, 0,
- manager_timeout, m);
- if (r < 0) {
- log_error("Failed to arm timeout timer: %s", strerror(-r));
- return r;
+ m->missed_replies++;
+ if (m->missed_replies > NTP_MAX_MISSED_REPLIES) {
+ r = sd_event_add_time(
+ m->event,
+ &m->event_timeout,
+ clock_boottime_or_monotonic(),
+ now(clock_boottime_or_monotonic()) + TIMEOUT_USEC, 0,
+ manager_timeout, m);
+ if (r < 0) {
+ log_error("Failed to arm timeout timer: %s", strerror(-r));
+ return r;
+ }
}
return 0;
@@ -549,6 +555,8 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
return 0;
}
+ m->missed_replies = 0;
+
/* check our "time cookie" (we just stored nanoseconds in the fraction field) */
if (be32toh(ntpmsg.origin_time.sec) != m->trans_time.tv_sec + OFFSET_1900_1970 ||
be32toh(ntpmsg.origin_time.frac) != m->trans_time.tv_nsec) {
@@ -712,6 +720,7 @@ static int manager_begin(Manager *m) {
assert_return(m->current_server_name, -EHOSTUNREACH);
assert_return(m->current_server_address, -EHOSTUNREACH);
+ m->missed_replies = NTP_MAX_MISSED_REPLIES;
m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
server_address_pretty(m->current_server_address, &pretty);
diff --git a/src/timesync/timesyncd-manager.h b/src/timesync/timesyncd-manager.h
index 0ac0e179c1..8296d41295 100644
--- a/src/timesync/timesyncd-manager.h
+++ b/src/timesync/timesyncd-manager.h
@@ -53,6 +53,7 @@ struct Manager {
ServerName *current_server_name;
ServerAddress *current_server_address;
int server_socket;
+ int missed_replies;
uint64_t packet_count;
sd_event_source *event_timeout;