timesync: make poll interval configurable

This adds PollIntervalMinSec= and PollIntervalMaxSec= to timesyncd.conf

Closes #7262.

5 files changed, 47 insertions, 22 deletions

diff --git a/src/timesync/timesyncd-conf.c b/src/timesync/timesyncd-conf.c
index f394d0a2af..b62e20c287 100644
--- a/src/timesync/timesyncd-conf.c
+++ b/src/timesync/timesyncd-conf.c
@@ -106,11 +106,27 @@ int config_parse_servers(
 }
 
 int manager_parse_config_file(Manager *m) {
+        int r;
+
         assert(m);
 
-        return config_parse_many_nulstr(PKGSYSCONFDIR "/timesyncd.conf",
-                                        CONF_PATHS_NULSTR("systemd/timesyncd.conf.d"),
-                                        "Time\0",
-                                        config_item_perf_lookup, timesyncd_gperf_lookup,
-                                        false, m);
+        r = config_parse_many_nulstr(PKGSYSCONFDIR "/timesyncd.conf",
+                                     CONF_PATHS_NULSTR("systemd/timesyncd.conf.d"),
+                                     "Time\0",
+                                     config_item_perf_lookup, timesyncd_gperf_lookup,
+                                     false, m);
+        if (r < 0)
+                return r;
+
+        if (m->poll_interval_min_usec < 16 * USEC_PER_SEC) {
+                log_warning("Invalid PollIntervalMinSec=. Using default value.");
+                m->poll_interval_min_usec = NTP_POLL_INTERVAL_MIN_USEC;
+        }
+
+        if (m->poll_interval_max_usec < m->poll_interval_min_usec) {
+                log_warning("PollIntervalMaxSec= is smaller than PollIntervalMinSec=. Using default value.");
+                m->poll_interval_max_usec = MAX(NTP_POLL_INTERVAL_MAX_USEC, m->poll_interval_min_usec * 32);
+        }
+
+        return r;
 }
diff --git a/src/timesync/timesyncd-gperf.gperf b/src/timesync/timesyncd-gperf.gperf
index 65fae9f1c9..e8ef5851e1 100644
--- a/src/timesync/timesyncd-gperf.gperf
+++ b/src/timesync/timesyncd-gperf.gperf
@@ -18,3 +18,5 @@ Time.NTP,                 config_parse_servers, SERVER_SYSTEM,   0
 Time.Servers,             config_parse_servers, SERVER_SYSTEM,   0
 Time.FallbackNTP,         config_parse_servers, SERVER_FALLBACK, 0
 Time.RootDistanceMaxSec,  config_parse_sec,     0,               offsetof(Manager, max_root_distance_usec)
+Time.PollIntervalMinSec,  config_parse_sec,     0,               offsetof(Manager, poll_interval_min_usec)
+Time.PollIntervalMaxSec,  config_parse_sec,     0,               offsetof(Manager, poll_interval_max_usec)
diff --git a/src/timesync/timesyncd-manager.c b/src/timesync/timesyncd-manager.c
index e58d819024..dad460f202 100644
--- a/src/timesync/timesyncd-manager.c
+++ b/src/timesync/timesyncd-manager.c
@@ -56,15 +56,8 @@
 #define NTP_ACCURACY_SEC                0.2
 
 /*
- * "A client MUST NOT under any conditions use a poll interval less
- * than 15 seconds."
- */
-#define NTP_POLL_INTERVAL_MIN_SEC       32
-#define NTP_POLL_INTERVAL_MAX_SEC       2048
-
-/*
  * Maximum delta in seconds which the system clock is gradually adjusted
- * (slew) to approach the network time. Deltas larger that this are set by
+ * (slewed) to approach the network time. Deltas larger that this are set by
  * letting the system time jump. The kernel's limit for adjtime is 0.5s.
  */
 #define NTP_MAX_ADJUST                  0.4
@@ -80,7 +73,7 @@
 #define NTP_FIELD_MODE(f)               ((f) & 7)
 #define NTP_FIELD(l, v, m)              (((l) << 6) | ((v) << 3) | (m))
 
-/* Maximum acceptable root distance in microseconds. */
+/* Default of maximum acceptable root distance in microseconds. */
 #define NTP_MAX_ROOT_DISTANCE           (5 * USEC_PER_SEC)
 
 /* Maximum number of missed replies before selecting another source. */
@@ -204,10 +197,10 @@ static int manager_send_request(Manager *m) {
 
         /* re-arm timer with increasing timeout, in case the packets never arrive back */
         if (m->retry_interval > 0) {
-                if (m->retry_interval < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
+                if (m->retry_interval < m->poll_interval_max_usec)
                         m->retry_interval *= 2;
         } else
-                m->retry_interval = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
+                m->retry_interval = m->poll_interval_min_usec;
 
         r = manager_arm_timer(m, m->retry_interval);
         if (r < 0)
@@ -446,27 +439,27 @@ static void manager_adjust_poll(Manager *m, double offset, bool spike) {
         assert(m);
 
         if (m->poll_resync) {
-                m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
+                m->poll_interval_usec = m->poll_interval_min_usec;
                 m->poll_resync = false;
                 return;
         }
 
         /* set to minimal poll interval */
         if (!spike && fabs(offset) > NTP_ACCURACY_SEC) {
-                m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
+                m->poll_interval_usec = m->poll_interval_min_usec;
                 return;
         }
 
         /* increase polling interval */
         if (fabs(offset) < NTP_ACCURACY_SEC * 0.25) {
-                if (m->poll_interval_usec < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
+                if (m->poll_interval_usec < m->poll_interval_max_usec)
                         m->poll_interval_usec *= 2;
                 return;
         }
 
         /* decrease polling interval */
         if (spike || fabs(offset) > NTP_ACCURACY_SEC * 0.75) {
-                if (m->poll_interval_usec > NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC)
+                if (m->poll_interval_usec > m->poll_interval_min_usec)
                         m->poll_interval_usec /= 2;
                 return;
         }
@@ -743,7 +736,7 @@ static int manager_begin(Manager *m) {
         m->good = false;
         m->missed_replies = NTP_MAX_MISSED_REPLIES;
         if (m->poll_interval_usec == 0)
-                m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
+                m->poll_interval_usec = m->poll_interval_min_usec;
 
         server_address_pretty(m->current_server_address, &pretty);
         log_debug("Connecting to time server %s (%s).", strna(pretty), m->current_server_name->string);
@@ -921,7 +914,7 @@ int manager_connect(Manager *m) {
                                 m->exhausted_servers = true;
 
                                 /* Increase the polling interval */
-                                if (m->poll_interval_usec < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
+                                if (m->poll_interval_usec < m->poll_interval_max_usec)
                                         m->poll_interval_usec *= 2;
 
                                 return 0;
@@ -1125,6 +1118,8 @@ int manager_new(Manager **ret) {
                 return -ENOMEM;
 
         m->max_root_distance_usec = NTP_MAX_ROOT_DISTANCE;
+        m->poll_interval_min_usec = NTP_POLL_INTERVAL_MIN_USEC;
+        m->poll_interval_max_usec = NTP_POLL_INTERVAL_MAX_USEC;
 
         m->server_socket = m->clock_watch_fd = -1;
 
diff --git a/src/timesync/timesyncd-manager.h b/src/timesync/timesyncd-manager.h
index 7550e828d0..d371f21f6a 100644
--- a/src/timesync/timesyncd-manager.h
+++ b/src/timesync/timesyncd-manager.h
@@ -25,11 +25,19 @@
 
 #include "list.h"
 #include "ratelimit.h"
+#include "time-util.h"
 
 typedef struct Manager Manager;
 
 #include "timesyncd-server.h"
 
+/*
+ * "A client MUST NOT under any conditions use a poll interval less
+ * than 15 seconds."
+ */
+#define NTP_POLL_INTERVAL_MIN_USEC      (32 * USEC_PER_SEC)
+#define NTP_POLL_INTERVAL_MAX_USEC      (2048 * USEC_PER_SEC)
+
 struct Manager {
         sd_event *event;
         sd_resolve *resolve;
@@ -67,6 +75,8 @@ struct Manager {
         /* poll timer */
         sd_event_source *event_timer;
         usec_t poll_interval_usec;
+        usec_t poll_interval_min_usec;
+        usec_t poll_interval_max_usec;
         bool poll_resync;
 
         /* history data */
diff --git a/src/timesync/timesyncd.conf.in b/src/timesync/timesyncd.conf.in
index 2b3c4764f9..f91c034a01 100644
--- a/src/timesync/timesyncd.conf.in
+++ b/src/timesync/timesyncd.conf.in
@@ -15,3 +15,5 @@
 #NTP=
 #FallbackNTP=@NTP_SERVERS@
 #RootDistanceMaxSec=5
+#PollIntervalMinSec=32
+#PollIntervalMaxSec=2048