[GE users] Re: [GE users] resource reservation not working

matbradford matthew.bradford at eds.com
Mon Aug 24 13:26:21 BST 2009


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>-----Original Message-----
>From: reuti [mailto:reuti at staff.uni-marburg.de]
>Sent: 24 August 2009 13:04
>To: users at gridengine.sunsource.net
>Subject: Re: [GE users] Re: [GE users] resource reservation not working
>
>Hiho,
>
>Am 24.08.2009 um 11:56 schrieb matbradford:
>
>> >> I think I was mistaken about reservation not working --- It just
>> doesn't
>> >> work the way I thought it would. What I expected was that, as
>> resources
>> >> (slots) came free, the scheduler would set them aside for the
>> reserving job
>> >> until it had accumulated enough to run it. Instead what happens
>> is that the
>> >> scheduler picks an arbitrary list of nodes that may *or may not*
>> have free
>> >> slots, and sets those slots aside as they come free. If slots
>> come free
>> >> that are *not* on this preselected list, they are cheerfully
>> assigned to
>> >> other
>> >> jobs, even those of lower priority than the reserving job.
>> >
>> >Could it be that these other nodes were actually not suited for this
>> >large parallel job? Reason could be 'oneper' is not contained in
>> >"pe_list" for the corresponding queue instances, reason could be
>> >resource requests with your job that can be satisfied only at a
>> subset
>> >of the queue instances, reason could be load thresholds with these
>> queue
>> >instances etc.
>> >
>> >>
>> >> The indirect evidence of this was right there in the monitor file
>> >> ($SGE_ROOT/$SGE_CE?LL/common/schedule) when I had it turned on,
>> but
>> >> I looked right past it: The reserving job has a list of queue
>> instances
>> >> associated
>> >> with it:
>> >>
>> >> 3568:1:RESERVING:119?0724115:660:P:oneper?:slots:20.000000
>> >> 3568:1:RESERVING:119?0724115:660:Q:all.q@?cl023:slots:
>> 1.000000?
>> >> 3568:1:RESERVING:119?0724115:660:Q:all.q@?cl026:slots:
>> 1.000000?
>> >>
>> >> ...and the list never changes! I suspect now that what happened
>> earlier was
>> >> that a node *not* on the reserved list came free, and the job I
>> thought was
>> >> violating the reservation policy was scheduled there. That's
>> certainly what
>> >> happened with some jobs that were scheduled last night.
>> >>
>> >> I suppose there ought to be a request-for-enhancement about
>> this: If
>> >> the scheduler were smart enough to glom resources *as they
>> became available*,
>> >> rather than preselecting them (who knows how?), then reservation
>> would
>> >> probably be a more effective function.
>> >
>> >Jobs' resource reservations are done anew with each scheduling
>> >interval. So actually the RFE is already implemented ;-)
>>
>> >
>> >Regards,
>> >Andreas
>>
>> Was this issue actually resolved, as we get the same issue.
>>
>> A user has submitted a job requiring 16 slots and the job is
>> sitting at the top of the pending queue, the scheduler has reserved
>> 16 slots for this job. At this point there were only 3 available
>> nodes,  and the scheduler correctly selected the free nodes, and 13
>> other nodes for reservation. No other small jobs were sitting in
>> the pending queue at this time. Subsequently, other smaller jobs
>> were submitted without a reservation request against them as they
>> only required 1 node. As running jobs finished, I would have
>> expected the scheduler to begin reserving the freed up nodes for
>> the 16 slot job at the top of the pending queue. This isn?t the
>> case, the reserved list of nodes isn?t changing and the smaller
>> jobs are still hopping over the large job.
>>
>> Any thoughts?
>>
>do you request h_rt or s_rt for oll the jobs?
We don't use an h_rt or s_rt value. The only setting that we have is default_duration set to 480 hours.
>
>==
>
>Or could it be related to this issue:
>
>http://gridengine.sunsource.net/issues/show_bug.cgi?id=2761
>
>Do you have any custom complexes?
We don't have any custom complexes against the queue, and against the nodes ,apart from the "slots" parameter, we only have static values such as rack number.
>
>-- Reuti
>
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