TTY task group scheduling

Julian Elischer julian at
Thu Nov 18 20:30:57 UTC 2010

On 11/18/10 10:55 AM, Lucius Windschuh wrote:
> 2010/11/18 Andriy Gapon<avg at>:
>> [Grouping of processes into TTY groups]
>> Well, I think that those improvements apply only to a very specific usage pattern
>> and are greatly over-hyped.
> But there are serious issue if you use FreeBSD as a desktop OS with
> SMP and SCHED_ULE, or?
> Because currently, my machine is barely usable if a compile job with
> parallelism is running. Movies stutter, Firefox hangs. And even nice
> -n 20 doesn't do the job in every case, as +20 seems not to be the
> idle priority anymore?!?
> And using "idprio 1 $cmd" as a workaround is, well, a kludge.
> I am not sure if TTY grouping is the right solution, if you look at
> potentially CPU-intensive GUI applications that all run on the same
> TTY (or no TTY at all? Same problem).
> Maybe, we could simply enhance the algorithm that decides if a task is
> interactive? That would also improve the described situation.

tty grouping is a variant of what we used to have at one stage which is
a "kernel schedulable entity group".. KSEG

the idea is that all items in a group share some characteristic and 
some amount
of resources.

We stripped the KSEG out of the picture because it really complicated 
the picture.

> Regards,
> Lucius
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