Heavy I/O blocks FreeBSD box for several seconds

[Steve Kargl]

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

-- 
Steve