Re: Periodic rant about SCHED_ULE

From: Mark Millard <marklmi_at_yahoo.com>
Date: Wed, 22 Mar 2023 17:09:20 UTC 
On Mar 22, 2023, at 09:48, Steve Kargl <sgk@troutmask.apl.washington.edu> wrote:

> 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

This referenced using:

% time /OpenMPI/mpiexec -machinefile mf -n 8 ./Test_mpi |& tee sgk.log

> 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.
> 

Looks like a csh context, so . . .

# csh
# time /OpenMPI/mpiexec -machinefile mf -n 8 ./Test_mpi |& tee sgk.log
/OpenMPI/mpiexec: Command not found.

That still leaves me trying to figure out an accurate
way to reproduce all the steps to have a comparable
way to see for myself.

===
Mark Millard
marklmi at yahoo.com