Heavy I/O blocks FreeBSD box for several seconds

Steve Kargl sgk at troutmask.apl.washington.edu
Wed Jul 6 16:28:12 UTC 2011

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.



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