Re: sysctl(7) knob to allow users to control CPU affinity

[Matthew Mondor <mm_lists%pulsar-zone.net@localhost>]

On Thu, 03 Nov 2011 17:01:48 +1100
matthew green <mrg%eterna.com.au@localhost> wrote:

> > Since the default is to not allow affinity control, it's not of utmost
> > importance, but it could allow a compromise between total restriction
> > and total freedom...  I have no objection to that sysctl personally.
> 
> i think the default should be changed, but user-specified affinity
> shouldn't be considered an absolute rule, just a preference.  i'm not
> sure i understand exactly what sort of issue you're envisioning.

I assumed there could be issues since pset(3) is restricted to the
superuser (as well as pthread_setaffinity_np(3) now), but when
rethinking about it I admit not seeing a problem as non-privileged
processes cannot change the process priority beyond their class'
priority.

The only other case that comes to my mind would be a dmover(9) like
system eventually reserving processor(s) for dedicated tasks, but I
guess that in this case the reserved cores would simply be made
unavailable in cpuctl(8)/pset(3)/etc...
-- 
Matt