timer: make timer accuracy configurable

And make it default to 1min

diff --git a/TODO b/TODO
index f84a24727b3c76498a551c5102f046d65af4a33d..04d92aba0387a323a839c4a1e8feeb534b59d023 100644 (file)
--- a/TODO
+++ b/TODO
@@ -466,8 +466,6 @@ Features:
 * deal with sendmail/postfix exclusivity
 
 * timer units:
 * deal with sendmail/postfix exclusivity
 
 * timer units:

-  - configurable jitter for timer events
-  - Adjust timers to be triggered at the same time as sd-event timers

   - timer events with system resume
   - timer units should get the ability to trigger when:
     o CLOCK_REALTIME makes jumps (TFD_TIMER_CANCEL_ON_SET)
   - timer events with system resume
   - timer units should get the ability to trigger when:
     o CLOCK_REALTIME makes jumps (TFD_TIMER_CANCEL_ON_SET)

diff --git a/man/systemd.timer.xml b/man/systemd.timer.xml
index 659bc81ccd9d69f2245c6d017b48a6a0687a5d1a..484287ccf67fc3f770f6883e8f7df6039e8b4d3e 100644 (file)
--- a/man/systemd.timer.xml
+++ b/man/systemd.timer.xml
@@ -163,7 +163,14 @@
                                 to any of these options, the list of
                                 timers is reset, and all prior
                                 assignments will have no
                                 to any of these options, the list of
                                 timers is reset, and all prior
                                 assignments will have no

-                                effect.</para></listitem>
+                                effect.</para>
+
+                                <para>Note that timers are not
+                                necessarily expired at the precise
+                                time configured with these settings,
+                                as they are subject to the
+                                <varname>AccuracySec=</varname>
+                                setting below.</para></listitem>

 
                         </varlistentry>
 
 
                         </varlistentry>
 


@@ -171,16 +178,61 @@
                                 <term><varname>OnCalendar=</varname></term>
 
                                 <listitem><para>Defines realtime
                                 <term><varname>OnCalendar=</varname></term>
 
                                 <listitem><para>Defines realtime

-                                (i.e. wallclock) timers via calendar
+                                (i.e. wallclock) timers with calendar

                                 event expressions. See
                                 <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>
                                 for more information on the syntax of
                                 calendar event expressions. Otherwise
                                 the semantics are similar to
                                 <varname>OnActiveSec=</varname> and
                                 event expressions. See
                                 <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>
                                 for more information on the syntax of
                                 calendar event expressions. Otherwise
                                 the semantics are similar to
                                 <varname>OnActiveSec=</varname> and

-                                related settings.</para></listitem>
+                                related settings.</para>
+
+                                <para>Note that timers are not
+                                necessarily expired at the precise
+                                time configured with this setting,
+                                as it is subject to the
+                                <varname>AccuracySec=</varname>
+                                setting below.</para></listitem>

                         </varlistentry>
 
                         </varlistentry>
 

+                        <varlistentry>
+                                <term><varname>AccuracySec=</varname></term>
+
+                                <listitem><para>Specify the accuracy
+                                the timer shall elapse with. Defaults
+                                to 1min. The timer is scheduled to
+                                expire within a time window starting
+                                with the time specified in
+                                <varname>OnCalendar=</varname>,
+                                <varname>OnActiveSec=</varname>,
+                                <varname>OnBootSec=</varname>,
+                                <varname>OnStartupSec=</varname>,
+                                <varname>OnUnitActiveSec=</varname> or
+                                <varname>OnUnitInactiveSec=</varname>
+                                and ending the time configured with
+                                <varname>AccuracySec=</varname>
+                                later. Within this time window the
+                                expiry time will be placed at a
+                                host-specific, randomized but stable
+                                position, that is synchronized between
+                                all local timer units. This is done in
+                                order to distribute the wake-up time
+                                in networked installations, as well as
+                                optimizing power consumption to
+                                suppress unnecessary CPU wake-ups. To
+                                get best accuracy set this option to
+                                1us. Note that the timer is still
+                                subject to the timer slack configured
+                                via
+                                <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
+                                <varname>TimerSlackNSec=</varname>
+                                setting. See
+                                <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+                                for details. To optimize power
+                                consumption make sure to set this
+                                value as high as possible and as low
+                                as necessary.</para></listitem>
+                        </varlistentry>

                         <varlistentry>
                                 <term><varname>Unit=</varname></term>
 
                         <varlistentry>
                                 <term><varname>Unit=</varname></term>
 


@@ -208,7 +260,9 @@
                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,

-                          <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+                          <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+                          <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                          <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>

                   </para>
         </refsect1>
 
                   </para>
         </refsect1>
 

diff --git a/src/core/dbus-timer.c b/src/core/dbus-timer.c
index 9e4070a1a356a5b78ee38a23d7f41f6d0ccc70a5..b7155219ef52de1026e0c7b62d8e683f63a8fbdc 100644 (file)
--- a/src/core/dbus-timer.c
+++ b/src/core/dbus-timer.c
@@ -143,6 +143,7 @@ const sd_bus_vtable bus_timer_vtable[] = {
         SD_BUS_PROPERTY("NextElapseUSecRealtime", "t", bus_property_get_usec, offsetof(Timer, next_elapse_monotonic), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
         SD_BUS_PROPERTY("NextElapseUSecMonotonic", "t", bus_property_get_usec, offsetof(Timer, next_elapse_realtime), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
         SD_BUS_PROPERTY("Result", "s", property_get_result, offsetof(Timer, result), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
         SD_BUS_PROPERTY("NextElapseUSecRealtime", "t", bus_property_get_usec, offsetof(Timer, next_elapse_monotonic), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
         SD_BUS_PROPERTY("NextElapseUSecMonotonic", "t", bus_property_get_usec, offsetof(Timer, next_elapse_realtime), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
         SD_BUS_PROPERTY("Result", "s", property_get_result, offsetof(Timer, result), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),

+        SD_BUS_PROPERTY("AccuracyUSec", "t", bus_property_get_usec, offsetof(Timer, accuracy_usec), 0),

         SD_BUS_VTABLE_END
 };
 
         SD_BUS_VTABLE_END
 };
 

diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
index 22dc536ee19ab1a3566302575255de86a3e669f0..fbf8381bc173745413171b9bc1c883dfe423e89b 100644 (file)
--- a/src/core/load-fragment-gperf.gperf.m4
+++ b/src/core/load-fragment-gperf.gperf.m4
@@ -247,6 +247,7 @@ Timer.OnBootSec,                 config_parse_timer,                 0,
 Timer.OnStartupSec,              config_parse_timer,                 0,                             0
 Timer.OnUnitActiveSec,           config_parse_timer,                 0,                             0
 Timer.OnUnitInactiveSec,         config_parse_timer,                 0,                             0
 Timer.OnStartupSec,              config_parse_timer,                 0,                             0
 Timer.OnUnitActiveSec,           config_parse_timer,                 0,                             0
 Timer.OnUnitInactiveSec,         config_parse_timer,                 0,                             0

+Timer.AccuracySec,               config_parse_sec,                   0,                             offsetof(Timer, accuracy_usec)

 Timer.Unit,                      config_parse_trigger_unit,          0,                             0
 m4_dnl
 Path.PathExists,                 config_parse_path_spec,             0,                             0
 Timer.Unit,                      config_parse_trigger_unit,          0,                             0
 m4_dnl
 Path.PathExists,                 config_parse_path_spec,             0,                             0

diff --git a/src/core/timer.c b/src/core/timer.c
index 5bc01a26ff796d23ce7e65514c5e3abafa72af5b..f23582c2db32e0f43d4d3b4f5a3d28665e8dcdd1 100644 (file)
--- a/src/core/timer.c
+++ b/src/core/timer.c
@@ -47,6 +47,7 @@ static void timer_init(Unit *u) {
 
         t->next_elapse_monotonic = (usec_t) -1;
         t->next_elapse_realtime = (usec_t) -1;
 
         t->next_elapse_monotonic = (usec_t) -1;
         t->next_elapse_realtime = (usec_t) -1;

+        t->accuracy_usec = USEC_PER_MINUTE;

 }
 
 void timer_free_values(Timer *t) {
 }
 
 void timer_free_values(Timer *t) {


@@ -144,6 +145,7 @@ static int timer_load(Unit *u) {
 }
 
 static void timer_dump(Unit *u, FILE *f, const char *prefix) {
 }
 
 static void timer_dump(Unit *u, FILE *f, const char *prefix) {

+        char buf[FORMAT_TIMESPAN_MAX];

         Timer *t = TIMER(u);
         Unit *trigger;
         TimerValue *v;
         Timer *t = TIMER(u);
         Unit *trigger;
         TimerValue *v;


@@ -153,10 +155,12 @@ static void timer_dump(Unit *u, FILE *f, const char *prefix) {
         fprintf(f,
                 "%sTimer State: %s\n"
                 "%sResult: %s\n"
         fprintf(f,
                 "%sTimer State: %s\n"
                 "%sResult: %s\n"

-                "%sUnit: %s\n",
+                "%sUnit: %s\n"
+                "%sAccuracy: %s\n",

                 prefix, timer_state_to_string(t->state),
                 prefix, timer_result_to_string(t->result),
                 prefix, timer_state_to_string(t->state),
                 prefix, timer_result_to_string(t->result),

-                prefix, trigger ? trigger->id : "n/a");
+                prefix, trigger ? trigger->id : "n/a",
+                prefix, format_timespan(buf, sizeof(buf), t->accuracy_usec, 1));

 
         LIST_FOREACH(value, v, t->values) {
 
 
         LIST_FOREACH(value, v, t->values) {
 


@@ -346,7 +350,7 @@ static void timer_enter_waiting(Timer *t, bool initial) {
 
                         r = sd_event_source_set_enabled(t->monotonic_event_source, SD_EVENT_ONESHOT);
                 } else
 
                         r = sd_event_source_set_enabled(t->monotonic_event_source, SD_EVENT_ONESHOT);
                 } else

-                        r = sd_event_add_monotonic(UNIT(t)->manager->event, t->next_elapse_monotonic, 0, timer_dispatch, t, &t->monotonic_event_source);
+                        r = sd_event_add_monotonic(UNIT(t)->manager->event, t->next_elapse_monotonic, t->accuracy_usec, timer_dispatch, t, &t->monotonic_event_source);

 
                 if (r < 0)
                         goto fail;
 
                 if (r < 0)
                         goto fail;


@@ -372,7 +376,7 @@ static void timer_enter_waiting(Timer *t, bool initial) {
 
                         r = sd_event_source_set_enabled(t->realtime_event_source, SD_EVENT_ONESHOT);
                 } else
 
                         r = sd_event_source_set_enabled(t->realtime_event_source, SD_EVENT_ONESHOT);
                 } else

-                        r = sd_event_add_realtime(UNIT(t)->manager->event, t->next_elapse_realtime, 0, timer_dispatch, t, &t->realtime_event_source);
+                        r = sd_event_add_realtime(UNIT(t)->manager->event, t->next_elapse_realtime, t->accuracy_usec, timer_dispatch, t, &t->realtime_event_source);

 
                 if (r < 0)
                         goto fail;
 
                 if (r < 0)
                         goto fail;

diff --git a/src/core/timer.h b/src/core/timer.h
index b3722f0028f325c2e618e864a4916d6dd1a162ef..3e7efa4c8370779fa3bff6423a9a982c74bc497c 100644 (file)
--- a/src/core/timer.h
+++ b/src/core/timer.h
@@ -69,6 +69,8 @@ typedef enum TimerResult {
 struct Timer {
         Unit meta;
 
 struct Timer {
         Unit meta;
 

+        usec_t accuracy_usec;
+

         LIST_HEAD(TimerValue, values);
         usec_t next_elapse_monotonic;
         usec_t next_elapse_realtime;
         LIST_HEAD(TimerValue, values);
         usec_t next_elapse_monotonic;
         usec_t next_elapse_realtime;

diff --git a/units/systemd-readahead-done.timer b/units/systemd-readahead-done.timer
index 41bfb2bd329bb7e9a4efecd2c4a8c60e57304f8d..bdfd4659136d0983f16d9855a3b59d631baafbeb 100644 (file)
--- a/units/systemd-readahead-done.timer
+++ b/units/systemd-readahead-done.timer
@@ -15,6 +15,7 @@ Before=shutdown.target
 
 [Timer]
 OnActiveSec=30s
 
 [Timer]
 OnActiveSec=30s

+AccuracySec=1s

 
 [Install]
 Also=systemd-readahead-collect.service
 
 [Install]
 Also=systemd-readahead-collect.service