Heavy I/O blocks FreeBSD box for several seconds

Hartmann, O. ohartman at zedat.fu-berlin.de
Thu Jul 7 05:52:44 UTC 2011

On 07/06/11 23:49, Oliver Pinter wrote:
> On 7/6/11, Hartmann, O.<ohartman at zedat.fu-berlin.de>  wrote:
>> 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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> http://lists.freebsd.org/pipermail/freebsd-stable/2010-September/thread.html#58537

The problem is not only related to desktop boxes, it involves servers 
with "big" hardware as well.

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