Am 11.10.2011 um 14:37 schrieb William Hay:

> On 11 October 2011 12:55, Reuti <[email protected]> wrote:
>> Am 10.10.2011 um 20:46 schrieb Gerald Ragghianti:
>> 
>>> We have a cluster consisting of 48-core compute nodes where we need to run 
>>> parallel (MPI) jobs across nodes.  There is a hardware limitation on the 
>>> QDR Infiniband cards that limits the available hardware contexts to 16 per 
>>> card.  We have to ensure that we don't over-subscribe these hardware 
>>> contexts because parallel jobs without available contexts will crash.  The 
>>> difficulty is that the contexts needed for a job are a function of the 
>>> number of compute nodes the job uses, not the number of job slots.
>> 
>> When I get you right, you are seeking for something like a complex with 
>> "consumable HOST" (instead of JOB or YES, i.e. consume it one time on each 
>> used exechost independent from the total number of slots granted on this 
>> machine). Unfortunately it was discussed before but not implemented yet.
>> 
>> 
> I don't think per host consumables would be needed.  With a later
> version of grid engine 2 queues should be sufficient.
> 1 queue with an exclusive resource and multi-node PEs and one without
> either of those.  You'd have to add a slots resource at the host level
> to stop the host being overloaded and possibly use a JSV to ensure all
> jobs are appropriately directed.
> 
> Unfortunately I don't think 6.1 supports exclusive resources.

Yep, that would be a possible implementation.

Like the OP mentioned, one could use a consumable complex for 6.1. If you add 
"complex_values network=16" to the queue, and "load_thresholds network=15" it 
will be pushed to alarm state automatically and you can avoid the load sensor. 
When you add a default consumption of 1, it works out-of-the-box (it's only 
subtracted if it's attached to a queue).

I.e. the other queue for normal jobs don't have it attached, and you select the 
special multi-node queue by the requested PE.

And as outlined: the overall slot count per node needs to be limited on an 
exechost level.

-- Reuti
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