<varlistentry>
<term><varname>RandomizedDelaySec=</varname></term>
- <listitem><para>Delay the timer by a randomly selected, evenly
- distributed amount of time between 0 and the specified time
- value. Defaults to 0, indicating that no randomized delay
- shall be applied. Each timer unit will determine this delay
- randomly before each iteration, and the delay will simply be
- added on top of the next determined elapsing time. This is
- useful to stretch dispatching of similarly configured timer
- events over a certain amount time, to avoid that they all fire
- at the same time, possibly resulting in resource
- congestion. Note the relation to
- <varname>AccuracySec=</varname> above: the latter allows the
- service manager to coalesce timer events within a specified
- time range in order to minimize wakeups, the former does the
- opposite: it stretches timer events over a time range, to make
- it unlikely that they fire simultaneously. If
- <varname>RandomizedDelaySec=</varname> and
- <varname>AccuracySec=</varname> are used in conjunction, first
- the randomized delay is added, and then the result is
- possibly further shifted to coalesce it with other timer
- events happening on the system. As mentioned above
- <varname>AccuracySec=</varname> defaults to 1min and
- <varname>RandomizedDelaySec=</varname> to 0, thus encouraging
- coalescing of timer events. In order to optimally stretch
- timer events over a certain range of time, make sure to set
- <varname>RandomizedDelaySec=</varname> to a higher value, and
- <varname>AccuracySec=1us</varname>.</para></listitem>
+ <listitem><para>Delay the timer by a randomly selected, evenly distributed amount of time between 0
+ and the specified time value. Defaults to 0, indicating that no randomized delay shall be applied.
+ Each timer unit will determine this delay randomly before each iteration, and the delay will simply
+ be added on top of the next determined elapsing time, unless modified with
+ <varname>FixedRandomDelay=</varname>, see below.</para>
+
+ <para>This setting is useful to stretch dispatching of similarly configured timer events over a
+ certain time interval, to prevent them from firing all at the same time, possibly resulting in
+ resource congestion.</para>
+
+ <para>Note the relation to <varname>AccuracySec=</varname> above: the latter allows the service
+ manager to coalesce timer events within a specified time range in order to minimize wakeups, while
+ this setting does the opposite: it stretches timer events over an interval, to make it unlikely that
+ they fire simultaneously. If <varname>RandomizedDelaySec=</varname> and
+ <varname>AccuracySec=</varname> are used in conjunction, first the randomized delay is added, and
+ then the result is possibly further shifted to coalesce it with other timer events happening on the
+ system. As mentioned above <varname>AccuracySec=</varname> defaults to 1 minute and
+ <varname>RandomizedDelaySec=</varname> to 0, thus encouraging coalescing of timer events. In order to
+ optimally stretch timer events over a certain range of time, set
+ <varname>AccuracySec=1us</varname> and <varname>RandomizedDelaySec=</varname> to some higher value.
+ </para></listitem>
</varlistentry>
<varlistentry>
<term><varname>FixedRandomDelay=</varname></term>
- <listitem><para>Takes a boolean argument. If true, some amount of time between 0 and
- <varname>RandomizedDelaySec=</varname> is chosen and added as the delay for each timer iteration. As this
- delay will not be recalculated on each run, this effectively creates a fixed offset for each iteration.
- The distribution between 0 and <varname>RandomizedDelaySec=</varname> is deterministic and based on
- a combination of the machine ID, whether the timer is run by the user/system manager, the service manager's
- user ID, and the timer's unit name. Has no effect if
- <varname>RandomizedDelaySec=</varname> is set to 0. Defaults to <option>false</option>.</para></listitem>
+ <listitem><para>Takes a boolean argument. When enabled, the randomized offset specified by
+ <varname>RandomizedDelaySec=</varname> is reused for all firings of the same timer. For a given timer
+ unit, the offset depends on the machine ID, user identifier and timer name, which means that it is
+ stable between restarts of the manager. This effectively creates a fixed offset for an individual
+ timer, reducing the jitter in firings of this timer, while still avoiding firing at the same time as
+ other similarly configured timers.</para>
+
+ <para>This setting has no effect if <varname>RandomizedDelaySec=</varname> is set to 0. Defaults to
+ <option>false</option>.</para></listitem>
</varlistentry>
<varlistentry>