Re: Should we add jitter to cron(8) ?

> On Nov 2, 2026, at 3:25 AM, Poul-Henning Kamp <phk@phk.freebsd.dk> wrote:
> 
> Embedded systems using cron(8) are starting to cause macroscopic
> effects at the top of the minute:
> 
> https://www.fz-juelich.de/en/news/archive/press-release/2026/mystery-of-60-second-fluctuations-in-power-grids-solved
> 
> That indicates that we should add jitter to cron(8).
> 
> I can see three ways to do it:
> 
> A) By default cron(8) waits [0...N] seconds before executing commands.
>   This can be disabled with a command line option.
>   For a number of reasons which we can hash later, I suggest N=30
> 
> B) Same as A), but the command line option enables jitter.
> 
> C) Same as A), but with additional crontab(5) syntax to say "dont
>   jitter this particular entry".
> 
> I would argue that A is the proper choice.
> 
> Comments ?

We can add a cron_flags="-s -j 30 -J 30" to /etc/defaults/rc.conf.

I suspect the % of embedded FreeBSD systems is rather low to matter.
Embedded Linux & various RTOSes will do their own thing in any case.