Heavy I/O blocks FreeBSD box for several seconds

Arnaud Lacombe lacombar at gmail.com
Wed Jul 6 19:44:09 UTC 2011


On Wed, Jul 6, 2011 at 12:28 PM, Steve Kargl
<sgk at 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
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 :-)

 - Arnaud

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