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diff --git a/man/systemd.timer.xml b/man/systemd.timer.xml
index fa67d59a2..484287ccf 100644
--- a/man/systemd.timer.xml
+++ b/man/systemd.timer.xml
@@ -128,7 +128,7 @@
combined of the same and of different
types. For example, by combining
OnBootSec= and
- OnUnitActiveSec= it is
+ OnUnitActiveSec=, it is
possible to define a timer that
elapses in regular intervals and
activates a specific service each
@@ -163,7 +163,14 @@
to any of these options, the list of
timers is reset, and all prior
assignments will have no
- effect.
+ effect.
+
+ Note that timers are not
+ necessarily expired at the precise
+ time configured with these settings,
+ as they are subject to the
+ AccuracySec=
+ setting below.
@@ -171,16 +178,61 @@
OnCalendar=
Defines realtime
- (i.e. wallclock) timers via calendar
+ (i.e. wallclock) timers with calendar
event expressions. See
systemd.time7
for more information on the syntax of
calendar event expressions. Otherwise
the semantics are similar to
OnActiveSec= and
- related settings.
+ related settings.
+
+ Note that timers are not
+ necessarily expired at the precise
+ time configured with this setting,
+ as it is subject to the
+ AccuracySec=
+ setting below.
+
+ AccuracySec=
+
+ 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
+ OnCalendar=,
+ OnActiveSec=,
+ OnBootSec=,
+ OnStartupSec=,
+ OnUnitActiveSec= or
+ OnUnitInactiveSec=
+ and ending the time configured with
+ AccuracySec=
+ 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
+ systemd-system.conf5's
+ TimerSlackNSec=
+ setting. See
+ prctl2
+ for details. To optimize power
+ consumption make sure to set this
+ value as high as possible and as low
+ as necessary.
+
Unit=
@@ -208,7 +260,9 @@
systemd.unit5,
systemd.service5,
systemd.time7,
- systemd.directives7
+ systemd.directives7,
+ systemd-system.conf5,
+ prctl2