[torqueusers] Curious question

Glen Beane glen.beane at gmail.com
Tue Mar 30 08:09:45 MDT 2010


On Tue, Mar 30, 2010 at 10:07 AM, Glen Beane <glen.beane at gmail.com> wrote:

>
>
> On Tue, Mar 30, 2010 at 9:55 AM, Charles Johnson <
> charles.johnson at accre.vanderbilt.edu> wrote:
>
>> About the nodes file ... I have always been under the impression that
>> the nodes file gives an ordering to nodes selected for jobs, i.e.,
>> nodes at the top of the list are considered before nodes at the
>> bottom. We are currently in a down time for refreshing hardware, and
>> the whole cluster is quiescent. As a test of hardware we submitted a
>> single job suitable for any one of several hundred nodes at the top of
>> the nodes file. The job ran on a node roughly halfway down the nodes
>> file. Again, there were no other jobs on the cluster.
>>
>> I am curious as to why? Any ideas?
>>
>> We are using torque 2.4.5 and moab 5.3.6
>>
>
>
> This is really a Moab question since Moab selects the node that the job
> will run on, it has nothing to do with the order of the nodes in the TORQUE
> node file. I think the default for Moab might be "last fit", so as it scans
> the available nodes it will select the last one it finds that satisfies the
> requirements for the job.  There is a "first fit" and "best fit" option if I
> remember correctly.
>
> With the fifo scheduler, then yes, I think the job would run on the first
> available node in the node list.
>

actually, I was thinking of LASTAVAILABLE, not "last fit", so the definition
would be different than what I stated.  This is the correct definition:
"This algorithm is a best fit in time algorithm that minimizes the impact of
reservation based node-time fragmentation."  I think this might be the
default, but I don't remember for sure.
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