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timesyncd: allow two missed replies before reselecting server

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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.
This commit is contained in:
Miroslav Lichvar 2014-09-02 14:29:51 +02:00 committed by Kay Sievers
parent 665c6a9eab
commit e8206972be
2 changed files with 19 additions and 9 deletions
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27
src/timesync/timesyncd-manager.c
View File

@ -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);

1
src/timesync/timesyncd-manager.h
View File

@ -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;