[GE users] job context and array tasks

Reuti reuti at staff.uni-marburg.de
Wed Nov 7 10:57:59 GMT 2007


Am 06.11.2007 um 15:09 schrieb Andy Schwierskott:

> Hi Mark,
>
>> Hi Andy,
>>
>>>    - have a handy syntax enhancement to set context variables for
>>> tasks and
>>>      ranges of tasks or all tasks, e.g.
>>>
>>>      qsub/qalter -Xc [flexible_range_specifier=]variable=value
>>>
>>>      where "flexible_range_specifier" at least should be the current
>>>      "task_id_range" (from the qsub syntax), but probably even a bit
>>> more
>>>      like support for adressing individual tasks:
>>>
>>>          2,3,6-12:2,18,100:4=restart=FALSE
>>
>>
>> A more flexible range specification would be also really useful  
>> for parallel
>> environments. For some calculations we need specialized domain
>> decomposition. We might, for example, decompose the domain into  
>> 12, 8, 6, 4
>> subdomains.  In which case one can't simply specify "-pe foo 4-12"  
>> and hope
>> for the best, but a finer grained control is needed:
>>  Eg, "-pe foo 4,6,8,12".
>>
>> Of course, this only makes sense when we can simultaneously  
>> specify masterq
>> resources too.
>
> and some more flexibility with wildcard PEs and ranges. :-)
>
> A customer told me that he would like to be able to ensure that  
> when a range
> is requested for a PE job which can go to different machines types on
> machine type A not more than 16 slots should be granted but on  
> machine type
> B up to 32 slots may be granted. Likely the only clean solution  
> would be to
> offer a true logical operation support for any types of resource  
> requests:
>
>    qsub "-pe sw1_machA 4-16 | -pe sw1_machB 4-32"
>
> Probably a more easy to implement solution would be to support a range
> specification in the PE configuration
>
>    qconf -sp sw1_machA
>    [...]
>    slot_range 4-16
>
>    qconf -sp sw1_machB
>    [...]
>    slot_range 4-32
>
> and the do a wildcard submission:
>
>    qsub -pe sw1_mach* 4-32
>
> Nevertheless that's now really a different story than the original  
> question
> about context variables.

Yep, we spoke already about it. Although I see the idea to put it  
(the ranges per PE) in the PE definition, you end up with more and  
more (nearly) identical PEs, especially if you want to limit the  
ranges per user(group) in addition (hence using user_lists) - which  
will give four PEs in this case potentially. With one change to the  
start_proc_args it might also be necessary to adjust several PEs in  
the same way.

Somehow I still have the feeling to put it in one resource quota is  
easier to handle - one resource quota with 4 rules instead of 4 PEs.  
But I also see a chance to combine it: the parser for quota-style  
limits is already in SGE, and so the interpreter. What about (and  
replacing slots, user_lists, xuser_lists):

$qconf -sp smp
pe_name           smp
limits            { \
                   limit to slots=150    # former slots setting for  
this PE; \
                   limit jobs {*} users @students to slots=4   #  
maximum slots per job for students; \
                   limit jobs {*} users @staff to slots=32    # in  
this case obsolete, as 32 is already the maximum set below; \
                   limit jobs {*} hosts @group_a to slot_range=4-16; \
                   limit jobs {*} hosts @group_b to  
slot_range=4-32    # in the last line w or w/o ; \
                   }
start_proc_args   /bin/true
stop_proc_args    /bin/true
allocation_rule   $round_robin
control_slaves    FALSE
job_is_first_task TRUE
urgency_slots     min

One side effect would be, that the binding of jobs to nodes connected  
to one and the same switch in the cluster could be coded as:

                   limit jobs {*} hosts @group_a to slot_range=4-16; \
                   limit jobs {*} hosts @group_b to slot_range=4-16; \
                   limit jobs {*} hosts @group_c to slot_range=4-16; \

Hence avoiding the former wildcard-PE solution. If you don't care  
where the jobs run leave it out or use:

                   limit jobs {*} hosts @group_a, @group_b, @group_c  
to slot_range=4-16; \

In contrast to resource quotas, all limits must be met in the set.

-- Reuti

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