Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Open MPI User's mailing list

Subject: Re: [OMPI users] Hybrid program
From: Gabriele Fatigati (g.fatigati_at_[hidden])
Date: 2008-11-20 09:42:24


Thanks Edgar,
but can i use these libraries also in a not NUMA machines?

2008/11/20 Edgar Gabriel <gabriel_at_[hidden]>:
> if you look at recent versions of libnuma, there are two functions called
> numa_run_on_node() and numa_run_on_node_mask(), which allow thread-based
> assignments to CPUs....
>
> Thanks
> Edgar
>
> Gabriele Fatigati wrote:
>>
>> Is there a way to assign one thread to one core? Also from code, not
>> necessary with OpenMPI option.
>>
>> Thanks.
>>
>> 2008/11/19 Stephen Wornom <stephen.wornom_at_[hidden]>:
>>>
>>> Gabriele Fatigati wrote:
>>>>
>>>> Ok,
>>>> but in Ompi 1.3 how can i enable it?
>>>>
>>> This may not be relevant, but I could not get a hybrid mpi+OpenMP code to
>>> work correctly.
>>> Would my problem be related to Gabriele's and perhaps fixed in openmpi
>>> 1.3?
>>> Stephen
>>>>
>>>> 2008/11/18 Ralph Castain <rhc_at_[hidden]>:
>>>>
>>>>> I am afraid it is only available in 1.3 - we didn't backport it to the
>>>>> 1.2
>>>>> series
>>>>>
>>>>>
>>>>> On Nov 18, 2008, at 10:06 AM, Gabriele Fatigati wrote:
>>>>>
>>>>>
>>>>>> Hi,
>>>>>> how can i set "slot mapping" as you told me? With TASK GEOMETRY? Or is
>>>>>> a new 1.3 OpenMPI feature?
>>>>>>
>>>>>> Thanks.
>>>>>>
>>>>>> 2008/11/18 Ralph Castain <rhc_at_[hidden]>:
>>>>>>
>>>>>>> Unfortunately, paffinity doesn't know anything about assigning
>>>>>>> threads
>>>>>>> to
>>>>>>> cores. This is actually a behavior of Linux, which only allows
>>>>>>> paffinity
>>>>>>> to
>>>>>>> be set at the process level. So, when you set paffinity on a process,
>>>>>>> you
>>>>>>> bind all threads of that process to the specified core(s). You cannot
>>>>>>> specify that a thread be given a specific core.
>>>>>>>
>>>>>>> In this case, your two threads/process are sharing the same core and
>>>>>>> thus
>>>>>>> contending for it. As you'd expect in that situation, one thread gets
>>>>>>> the
>>>>>>> vast majority of the attention, while the other thread is mostly
>>>>>>> idle.
>>>>>>>
>>>>>>> If you can upgrade to the beta 1.3 release, try using the slot
>>>>>>> mapping
>>>>>>> to
>>>>>>> assign multiple cores to each process. This will ensure that the
>>>>>>> threads
>>>>>>> for
>>>>>>> that process have exclusive access to those cores, but will not bind
>>>>>>> a
>>>>>>> particular thread to one core - the threads can "move around" across
>>>>>>> the
>>>>>>> specified set of cores. Your threads will then be able to run without
>>>>>>> interfering with each other.
>>>>>>>
>>>>>>> Ralph
>>>>>>>
>>>>>>>
>>>>>>> On Nov 18, 2008, at 9:18 AM, Gabriele Fatigati wrote:
>>>>>>>
>>>>>>>
>>>>>>>> Dear OpenMPI developers,
>>>>>>>> i have a strange problem with mixed program MPI+OPENMP over OpenMPI
>>>>>>>> 1.2.6. I'm using PJL TASK GEOMETRY in LSF Scheduler, setting 2 MPI
>>>>>>>> process every compute node, and 2 OMP threads per process. Using
>>>>>>>> paffinity and maffinity, i've noted that over every node, i have 2
>>>>>>>> thread that works 100%, and 2 threads doesn't works, or works very
>>>>>>>> few.
>>>>>>>>
>>>>>>>> If i disable paffinity and maffinity, 4 threads works well, without
>>>>>>>> load imbalance.
>>>>>>>> I don't understand this issue: paffinity and maffinity should map
>>>>>>>> every thread over a specific core, optimizing the cache flow, but i
>>>>>>>> have this without settings there!
>>>>>>>>
>>>>>>>> Can i use paffinity and maffinity in mixed MPI+OpenMP program? Or it
>>>>>>>> works only over MPI thread?
>>>>>>>>
>>>>>>>> Thanks in advance.
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Ing. Gabriele Fatigati
>>>>>>>>
>>>>>>>> CINECA Systems & Tecnologies Department
>>>>>>>>
>>>>>>>> Supercomputing Group
>>>>>>>>
>>>>>>>> Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy
>>>>>>>>
>>>>>>>> www.cineca.it Tel: +39 051 6171722
>>>>>>>>
>>>>>>>> g.fatigati_at_[hidden]
>>>>>>>> _______________________________________________
>>>>>>>> users mailing list
>>>>>>>> users_at_[hidden]
>>>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> users mailing list
>>>>>>> users_at_[hidden]
>>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>> --
>>>>>> Ing. Gabriele Fatigati
>>>>>>
>>>>>> CINECA Systems & Tecnologies Department
>>>>>>
>>>>>> Supercomputing Group
>>>>>>
>>>>>> Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy
>>>>>>
>>>>>> www.cineca.it Tel: +39 051 6171722
>>>>>>
>>>>>> g.fatigati_at_[hidden]
>>>>>> _______________________________________________
>>>>>> users mailing list
>>>>>> users_at_[hidden]
>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>>>
>>>>> _______________________________________________
>>>>> users mailing list
>>>>> users_at_[hidden]
>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>> --
>>> stephen.wornom_at_[hidden]
>>> 2004 route des lucioles - BP93
>>> Sophia Antipolis
>>> 06902 CEDEX
>>>
>>> Tel: 04 92 38 50 54
>>> Fax: 04 97 15 53 51
>>>
>>>
>>> _______________________________________________
>>> users mailing list
>>> users_at_[hidden]
>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>
>>
>>
>>
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users
>
>

-- 
Ing. Gabriele Fatigati
CINECA Systems & Tecnologies Department
Supercomputing  Group
Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy
www.cineca.it                    Tel:   +39 051 6171722
g.fatigati_at_[hidden]