TTY task group scheduling

O. Hartmann ohartman at
Thu Nov 18 20:30:18 UTC 2010

On 11/18/10 19:55, 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.
> Regards,
> Lucius

Stuttering Response, being stuck for over 20 seconds also happens when I 
start updating the OS' sources via svn. This happens on all boxes, some 
of them do have 8 cores (ob two CPUs) and plenty of RAM. Heavy disk I/O, 
doesn't matter on UFS2 or ZFS, also brings boxes to stutter, those 
phenomena are most seen when you interact with the machine via X11 
clients. I think it's hard to realize if a server only does console I/O, 
but console also seems to be stuck sometimes. It would be worth checking 
this with some 'benchmark'. X11 in its kind of oldish incarnation on 
FreeBSD seems to contribute most to those slowdowns, what so ever.

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