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Date:      Mon, 12 Dec 2011 16:18:35 +0000
From:      Bruce Cran <bruce@cran.org.uk>
To:        Steve Kargl <sgk@troutmask.apl.washington.edu>
Cc:        "O. Hartmann" <ohartman@mail.zedat.fu-berlin.de>, Current FreeBSD <freebsd-current@freebsd.org>, freebsd-stable@freebsd.org, freebsd-performance@freebsd.org
Subject:   Re: SCHED_ULE should not be the default
Message-ID:  <4EE6295B.3020308@cran.org.uk>
In-Reply-To: <20111212155159.GB73597@troutmask.apl.washington.edu>
References:  <4EE1EAFE.3070408@m5p.com> <4EE22421.9060707@gmail.com> <4EE6060D.5060201@mail.zedat.fu-berlin.de> <20111212155159.GB73597@troutmask.apl.washington.edu>

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On 12/12/2011 15:51, Steve Kargl wrote:
> This comes up every 9 months or so, and must be approaching FAQ 
> status. In a HPC environment, I recommend 4BSD. Depending on the 
> workload, ULE can cause a severe increase in turn around time when 
> doing already long computations. If you have an MPI application, 
> simply launching greater than ncpu+1 jobs can show the problem. PS: 
> search the list archives for "kargl and ULE". 

This isn't something that can be fixed by tuning ULE? For example for 
desktop applications kern.sched.preempt_thresh should be set to 224 from 
its default. I'm wondering if the installer should ask people what the 
typical use will be, and tune the scheduler appropriately.

-- 
Bruce Cran



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