kern.sched.quantum: Creepy, sadistic scheduler

Peter pmc at
Wed Apr 4 14:35:04 UTC 2018

George Mitchell wrote:
> On 04/04/18 06:39, Alban Hertroys wrote:
>> [...]
>> That said, SCHED_ULE (the default scheduler for quite a while now) was designed with multi-CPU configurations in mind and there are claims that SCHED_4BSD works better for single-CPU configurations. You may give that a try, if you're not already on SCHED_4BSD.
>> [...]
> A small, disgruntled community of FreeBSD users who have never seen
> proof that SCHED_ULE is better than SCHED_4BSD in any environment
> continue to regularly recompile with SCHED_4BSD.  I dread the day when
> that becomes impossible, but at least it isn't here yet.      -- George

Yes *laugh*, I found a very lengthy and mind-boggling discussion from 
back in 2011. And I found that You made this statement somewhere there:

// With nCPU compute-bound processes running, with SCHED_ULE, any other
// process that is interactive (which to me means frequently waiting for
// I/O) gets ABYSMAL performance -- over an order of magnitude worse
// than it gets with SCHED_4BSD under the same conditions. --

And this describes quite exactly what I perceive.
Now, I would like to ask: what has been done about this issue?


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