diff options
Diffstat (limited to 'man/systemd.timer.xml')
| -rw-r--r-- | man/systemd.timer.xml | 62 |
1 files changed, 58 insertions, 4 deletions
diff --git a/man/systemd.timer.xml b/man/systemd.timer.xml index 659bc81ccd..484287ccf6 100644 --- 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 - 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> @@ -171,17 +178,62 @@ <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 - 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> + <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> <listitem><para>The unit to activate @@ -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.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> |