On 02/11/2026 12:25, Poul-Henning Kamp 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 already have that. Or do you mean something else? -j jitter Enable time jitter. Prior to executing commands, cron will sleep a random number of seconds in the range from 0 to jitter. This will not affect superuser jobs (see -J). A value for jitter must be between 0 and 60 inclusive. Default is 0, which effectively disables time jitter. This option can help to smooth down system load spikes during moments when a lot of jobs are likely to start at once, e.g., at the beginning of the first minute of each hour. -J rootjitter Enable time jitter for superuser jobs. The same as -j except that it will affect jobs run by the superuser only. cron_flags="-j 20 -J 20" in rc.conf should do the trick Best regards Miroslav Lachman
