Re: Periodic rant about SCHED_ULE

From: Matthias Andree <>
Date: Wed, 22 Mar 2023 10:17:51 UTC
Am 21.03.23 um 23:52 schrieb George Mitchell:
> Yes, you've all heard it before, but I've just reverified on FreeBSD
> 13.1-RELEASE-p7 that SCHED_ULE gives terrible performance for "make
> buildworld" in the presence of a totally compute-bound job (misc/dnetc
> from ports) running at nice 20.  World builds in:
> 15597 seconds with SCHED_4BSD without dnetc
> 20477 seconds with SCHED_4BSD with dnetc
> 16006 seconds with SCHED_ULE without dnetc
> 50290 seconds with SCHED_ULE with dnetc.
> When I ask why SCHED_ULE is the default scheduler, I have been told more
> than once that there is some circumstance in which it gives superior
> performance.  But no one seems to know what circumstance that is.  Guess
> what!  I propose that SCHED_4BSD be the default scheduler.     -- George

Can you please also give figures how much CPU time has been allotted to 
dnetc in that respective situations?

Matthias Andree