Heavy I/O blocks FreeBSD box for several seconds

Hartmann, O. ohartman at zedat.fu-berlin.de
Wed Jul 6 21:00:24 UTC 2011

On 07/06/11 21:36, Steve Kargl wrote:
> 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 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
>> [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.
Well, I know only very little people using FreeBSD within a HPC cluster 
or even for scientific purposes, except myself and some people around here.

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