[GE users] Can I stop backfilling?

Daniel Templeton Dan.Templeton at Sun.COM
Tue May 20 16:44:45 BST 2008


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Reuti wrote:
> Am 20.05.2008 um 17:15 schrieb Daniel Templeton:
>
>> If your jobs are starving, what you're seeing is not backfilling. :)  
>> What version of SGE are you using?  There was (is?) a bug where the 
>> first RR job was ignored.  Submitting a second identical RR job, in 
>> that case, would then cause the scheduler to take notice and actually 
>> do the RR properly.
>>
>> By definition, backfilling cannot cause starvation, unless a 
>> backfilled job runs forever.
>
> Good point. What h_rt is requested by these short jobs? Otherwise the 
> default_duration will be taken (but not enforced) and this might lead 
> to a roll-over from one extending job (running longer than the 
> estimated default 10 minutes) to the next one and so onI fear.

That will happen once, but not repeatedly.  After the first jobs 
overruns its estimated run time, the scheduler will treat the overrun is 
as ending "immediately" and won't do any more backfilling.

Daniel

>
>>   BTW, when you say your jobs run 15-20 minutes, are they setting 
>> sort or hard run time limits?  If not, what is your default_duration?
>>
>> Daniel
>>
>> Kevin Doman wrote:
>>> We have a very busy cluster that always have thousands of short jobs
>>> (15-20 minutes) in queue. Occasionally, a user come in and submit a 20
>>> processor parallel job with h_rt=100 hours. While reservation is
>>> enabled (-R y) and priority set to 1024, we continue to experience job
>
> max_reservation is also set up to a sensible value?
>
> -- Reuti
>
>
>>> backfills which resulted in the same 'parallel job starvation' issue.
>>>
>>> Is it possible for me to stop backfilling altogether and let the
>>> parallel jobs go first?
>>>
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