Re: Periodic rant about SCHED_ULE

From: Steve Kargl <sgk_at_troutmask.apl.washington.edu>
Date: Wed, 22 Mar 2023 16:48:17 UTC 
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.

-- 
Steve