kern.sched.quantum: Creepy, sadistic scheduler

Peter pmc at
Sat Apr 7 01:13:35 UTC 2018

Eugene Grosbein wrote:

> I see no reasons to use SHED_ULE for such single core systems and use SCHED_BSD.

Nitpicking: it is not a single core system, it's a dual that for now is 
equipped with only one chip, the other is in the shelf.

But seriously, I am currently working myself through the design papers
for the SCHED_ULE and the SMP stuff, and I tend to be with You and 
George, in that I do not really need these features.

Nevertheless, I think the system should have proper behaviour *as 
default*, or otherwise there should be a hint in the docs what to do about.
Thats the reason why I raise this issue - if the matter can be fixed, 
thats great, but if we come to the conclusion that 
small/single-core/CPU-bound/whatever systems are better off with 
SCHED_4BSD, then thats perfectly fine as well. Or maybe, that those 
systems should disable preemption? I currently don't know, but i hope we 
can figure this out, as the problem is clearly visible.


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