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Date: Wed, 6 Jul 2011 12:36:36 -0700
From: Steve Kargl <sgk@troutmask.apl.washington.edu>
To: Arnaud Lacombe <lacombar@gmail.com>
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Cc: FreeBSD Current <freebsd-current@freebsd.org>,
	"O. Hartmann" <ohartman@zedat.fu-berlin.de>,
	arrowdodger <6yearold@gmail.com>, freebsd-questions@freebsd.org
Subject: Re: Heavy I/O blocks FreeBSD box for several seconds
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On Wed, Jul 06, 2011 at 03:18:35PM -0400, Arnaud Lacombe wrote:
> Hi,
> 
> On Wed, Jul 6, 2011 at 12:28 PM, Steve Kargl
> <sgk@troutmask.apl.washington.edu> 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
> >
> [sarcasm]
> It is rather funny to see that the post you point out has generated
> exactly 0 meaningful follow-up then and as you mention later in this
> thread, the issue still remains today :-)
> [/sarcasm]
> 

Apparently, you are privy to my private email exchanges
with jeffr.

I'm also not sure why you're being sarcastic here.  The
issue was and AFAIK still is a problem for anyone using
FreeBSD in a HPC cluster.  ULE simply performs worse than
4BSD.

-- 
Steve