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Date:      Wed, 22 Mar 2023 10:10:43 -0700 (PDT)
From:      "Rodney W. Grimes" <freebsd-rwg@gndrsh.dnsmgr.net>
To:        sgk@troutmask.apl.washington.edu
Cc:        Mark Millard <marklmi@yahoo.com>, George Mitchell <george+freebsd@m5p.com>, FreeBSD Hackers <freebsd-hackers@FreeBSD.org>
Subject:   Re: Periodic rant about SCHED_ULE
Message-ID:  <202303221710.32MHAhe9047582@gndrsh.dnsmgr.net>
In-Reply-To: <ZBsxUYQwqHvuIdpe@troutmask.apl.washington.edu>

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> 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



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