Re: Periodic rant about SCHED_ULE

> On Wed, Mar 22, 2023 at 09:20:27AM -0700, Mark Millard wrote:
> > 
> > Giving folks a way to know they are repeating your tests
> > appropriately, could give interested folks a way to answer
> > their own questions.
> 
> This has been an issue for years (and now stretching into
> decades).  It is trivial to show the problem with any
> numerically intensive MPI program.  I've done this a few
> times, and reported the issues. Search the mailing list
> archives, e.g., 
> 
> https://lists.freebsd.org/pipermail/freebsd-hackers/2008-October/026375.html
> 
> It appears to be (or was) an issue with cpu affinity.
> 
> Caveat: I haven't tested this in a long time.  I simple use 4BSD.

I dont even try ULE any more.  I just used 4BSD, as did bde@freebsd.org,
ULE seems to suck when your have interactive use and compute bound on
the same  box.  I have seen interactive in the past take seconds to
echo a command.  IIRC ULE and zfs in a memory contrained environment
dont play nicely togeather either.

+1 on the return to 4BSD as the default scheduler


-- 
Rod Grimes                                                 rgrimes@freebsd.org