Heavy I/O blocks FreeBSD box for several seconds
sgk at troutmask.apl.washington.edu
Wed Jul 6 17:01:33 UTC 2011
On Wed, Jul 06, 2011 at 06:38:23PM +0200, Hartmann, O. wrote:
> 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.
> Worth a try,
> but most of my code I use is OpenMP, not MPI.
It may impact OpenMP. I don't have any OpenMP to test. But,
if OpenMP is spawning as many or more threads than the number
of available processors/cores, then I think you will have
> The post is of 2008, that's three years ago and 9.0 is on the brink to
> become released ...
I periodically ran the same type test in the 2008 post over the
last three years. Nothing has changed. I even set up an account
on one node in my cluster for jeffr to use. He was too busy to
investigate at that time.
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