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Date: Wed, 06 Jul 2011 18:38:23 +0200
From: "Hartmann, O." <ohartman@zedat.fu-berlin.de>
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To: Steve Kargl <sgk@troutmask.apl.washington.edu>
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Cc: FreeBSD Current <freebsd-current@freebsd.org>,
	arrowdodger <6yearold@gmail.com>, freebsd-questions@freebsd.org
Subject: Re: Heavy I/O blocks FreeBSD box for several seconds
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On 07/06/11 18:28, Steve Kargl wrote:
> On Wed, Jul 06, 2011 at 05:29:24PM +0200, O. Hartmann wrote:
>> I use SCHED_ULE on all machines, since it is supposed to be performing
>> better on multicore boxes, but there are lots of suggestions switching
>> back to the old SCHED_4BSD scheduler.
>>
> If you are using MPI in numerical codes, then you want
> to use SCHED_4BSD.  I've posted numerous times about ULE
> and its very poor performance when using MPI.
>
> http://lists.freebsd.org/pipermail/freebsd-hackers/2008-October/026375.html
>

Worth a try,
but most of my code I use is OpenMP, not MPI.

The post is of 2008, that's three years ago and 9.0 is on the brink to 
become released ...