On: The mystery of the fifteen-millisecond breakpoint instruction

[JoachimSchipper]

You need quite a few kernel<->userland switches in this case, maybe that's enough?

[TheLoneWolfling → JoachimSchipper]

Potentially, although in that case it's still dsyslog's fault.

[ars → TheLoneWolfling]

It's classed as an ALERT level message, so rsyslog will sync after outputting it. That might account for the time.