Re: [EXT] Re: Understanding the effect of AccuracySec=

[Andrei Borzenkov <arvidjaar@xxxxxxxxx>]

On Mon, Aug 19, 2024 at 10:11 AM Barry <barry@xxxxxxxxxxxxxxxx> wrote:
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> On 19 Aug 2024, at 06:55, Windl, Ulrich <u.windl@xxxxxx> wrote:
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> Despite of the fact that my version of systemd does not know that setting, can you explain what the effect of AccuracySec= really is?
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> The docs https://www.man7.org/linux/man-pages/man5/systemd.timer.5.html say this
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>  Note that this setting is primarily a power saving option
>            that allows coalescing CPU wake-ups. It should not be
>            confused with RandomizedDelaySec= (see below) which adds a
>            random value to the time the timer shall elapse next and
>            whose purpose is the opposite: to stretch elapsing of timer
>            events over a longer period to reduce workload spikes. For
>            further details and explanations and how both settings play
>            together, see below.
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> So if you have 5 timers that expire about the same time this allows them to all run at the sane time thus saving power.

It does explain why timers are run at the same time. It does not
explain why "daily" + accuracy 6h runs at midnight, not close to 6am