Re: Periodic rant about SCHED_ULE

From: Matthias Andree <>
Date: Wed, 22 Mar 2023 18:31:57 UTC
Am 22.03.23 um 15:41 schrieb George Mitchell:
> On 3/22/23 06:17, Matthias Andree wrote:
>> Am 21.03.23 um 23:52 schrieb George Mitchell:
>>> Yes, you've all heard it before [... blah blah blah ...]
>> Can you please also give figures how much CPU time has been allotted 
>> to dnetc in that respective situations?
> I let the scheduler do the time allocation.  The result is that dnetc
> gobbles whatever time remains available when higher priority processes
> (i.e. every other process on the system) have nothing to do.  With
> SCHED_4BSD the resulting idle time is 0 (as reported by top).  I did
> not take note of the idle time when I was doing the SCHED_ULE run.

You are not answering my question.  I asked how much time did dnetc use 
in the time where you were doing your test compile.

The next question is then where you get the idea that a scheduler must 
interpret 20 as "only if idle". Linux has scheduling classes with "idle" 
and "best-effort" priority classes, for one.

Yes, there are reports that FreeBSD is not responsive by default - but 
this may make it get overall better throughput at the expense of 
responsiveness, because it might be doing fewer context switches.  So 
just complaining about a longer buildworld without seeing how much dnetc 
did in the same wallclock time period is useless.  Periodic rant's don't 
fix this lack of information.

Matthias Andree
FreeBSD ports committer