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Subject: Re: [OMPI users] [openib] segfault when using openib btl
From: Edgar Gabriel (gabriel_at_[hidden])
Date: 2010-07-15 11:24:24


On 7/15/2010 10:18 AM, Eloi Gaudry wrote:
> hi edgar,
>
> thanks for the tips, I'm gonna try this option as well. the segmentation fault i'm observing always happened during a collective communication indeed...
> does it basically switch all collective communication to basic mode, right ?
>
> sorry for my ignorance, but what's a NCA ?

sorry, I meant to type HCA (InifinBand networking card)

Thanks
Edgar

>
> thanks,
> éloi
>
> On Thursday 15 July 2010 16:20:54 Edgar Gabriel wrote:
>> you could try first to use the algorithms in the basic module, e.g.
>>
>> mpirun -np x --mca coll basic ./mytest
>>
>> and see whether this makes a difference. I used to observe sometimes a
>> (similar ?) problem in the openib btl triggered from the tuned
>> collective component, in cases where the ofed libraries were installed
>> but no NCA was found on a node. It used to work however with the basic
>> component.
>>
>> Thanks
>> Edgar
>>
>> On 7/15/2010 3:08 AM, Eloi Gaudry wrote:
>>> hi Rolf,
>>>
>>> unfortunately, i couldn't get rid of that annoying segmentation fault
>>> when selecting another bcast algorithm. i'm now going to replace
>>> MPI_Bcast with a naive implementation (using MPI_Send and MPI_Recv) and
>>> see if that helps.
>>>
>>> regards,
>>> éloi
>>>
>>> On Wednesday 14 July 2010 10:59:53 Eloi Gaudry wrote:
>>>> Hi Rolf,
>>>>
>>>> thanks for your input. You're right, I miss the
>>>> coll_tuned_use_dynamic_rules option.
>>>>
>>>> I'll check if I the segmentation fault disappears when using the basic
>>>> bcast linear algorithm using the proper command line you provided.
>>>>
>>>> Regards,
>>>> Eloi
>>>>
>>>> On Tuesday 13 July 2010 20:39:59 Rolf vandeVaart wrote:
>>>>> Hi Eloi:
>>>>> To select the different bcast algorithms, you need to add an extra mca
>>>>> parameter that tells the library to use dynamic selection.
>>>>> --mca coll_tuned_use_dynamic_rules 1
>>>>>
>>>>> One way to make sure you are typing this in correctly is to use it with
>>>>> ompi_info. Do the following:
>>>>> ompi_info -mca coll_tuned_use_dynamic_rules 1 --param coll
>>>>>
>>>>> You should see lots of output with all the different algorithms that
>>>>> can be selected for the various collectives.
>>>>> Therefore, you need this:
>>>>>
>>>>> --mca coll_tuned_use_dynamic_rules 1 --mca coll_tuned_bcast_algorithm 1
>>>>>
>>>>> Rolf
>>>>>
>>>>> On 07/13/10 11:28, Eloi Gaudry wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I've found that "--mca coll_tuned_bcast_algorithm 1" allowed to switch
>>>>>> to the basic linear algorithm. Anyway whatever the algorithm used, the
>>>>>> segmentation fault remains.
>>>>>>
>>>>>> Does anyone could give some advice on ways to diagnose the issue I'm
>>>>>> facing ?
>>>>>>
>>>>>> Regards,
>>>>>> Eloi
>>>>>>
>>>>>> On Monday 12 July 2010 10:53:58 Eloi Gaudry wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> I'm focusing on the MPI_Bcast routine that seems to randomly segfault
>>>>>>> when using the openib btl. I'd like to know if there is any way to
>>>>>>> make OpenMPI switch to a different algorithm than the default one
>>>>>>> being selected for MPI_Bcast.
>>>>>>>
>>>>>>> Thanks for your help,
>>>>>>> Eloi
>>>>>>>
>>>>>>> On Friday 02 July 2010 11:06:52 Eloi Gaudry wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> I'm observing a random segmentation fault during an internode
>>>>>>>> parallel computation involving the openib btl and OpenMPI-1.4.2 (the
>>>>>>>> same issue can be observed with OpenMPI-1.3.3).
>>>>>>>>
>>>>>>>> mpirun (Open MPI) 1.4.2
>>>>>>>> Report bugs to http://www.open-mpi.org/community/help/
>>>>>>>> [pbn08:02624] *** Process received signal ***
>>>>>>>> [pbn08:02624] Signal: Segmentation fault (11)
>>>>>>>> [pbn08:02624] Signal code: Address not mapped (1)
>>>>>>>> [pbn08:02624] Failing at address: (nil)
>>>>>>>> [pbn08:02624] [ 0] /lib64/libpthread.so.0 [0x349540e4c0]
>>>>>>>> [pbn08:02624] *** End of error message ***
>>>>>>>> sh: line 1: 2624 Segmentation fault
>>>>>>>>
>>>>>>>> \/share\/hpc3\/actran_suite\/Actran_11\.0\.rc2\.41872\/RedHatEL\-5\/
>>>>>>>> x 86 _6 4\ /bin\/actranpy_mp
>>>>>>>> '--apl=/share/hpc3/actran_suite/Actran_11.0.rc2.41872/RedHatEL-5/x86
>>>>>>>> _ 64 /A c tran_11.0.rc2.41872'
>>>>>>>> '--inputfile=/work/st25652/LSF_130073_0_47696_0/Case1_3Dreal_m4_n2.d
>>>>>>>> a t' '--scratch=/scratch/st25652/LSF_130073_0_47696_0/scratch'
>>>>>>>> '--mem=3200' '--threads=1' '--errorlevel=FATAL' '--t_max=0.1'
>>>>>>>> '--parallel=domain'
>>>>>>>>
>>>>>>>> If I choose not to use the openib btl (by using --mca btl
>>>>>>>> self,sm,tcp on the command line, for instance), I don't encounter
>>>>>>>> any problem and the parallel computation runs flawlessly.
>>>>>>>>
>>>>>>>> I would like to get some help to be able:
>>>>>>>> - to diagnose the issue I'm facing with the openib btl
>>>>>>>> - understand why this issue is observed only when using the openib
>>>>>>>> btl and not when using self,sm,tcp
>>>>>>>>
>>>>>>>> Any help would be very much appreciated.
>>>>>>>>
>>>>>>>> The outputs of ompi_info and the configure scripts of OpenMPI are
>>>>>>>> enclosed to this email, and some information on the infiniband
>>>>>>>> drivers as well.
>>>>>>>>
>>>>>>>> Here is the command line used when launching a parallel computation
>>>>>>>>
>>>>>>>> using infiniband:
>>>>>>>> path_to_openmpi/bin/mpirun -np $NPROCESS --hostfile host.list
>>>>>>>> --mca
>>>>>>>>
>>>>>>>> btl openib,sm,self,tcp --display-map --verbose --version --mca
>>>>>>>> mpi_warn_on_fork 0 --mca btl_openib_want_fork_support 0 [...]
>>>>>>>>
>>>>>>>> and the command line used if not using infiniband:
>>>>>>>> path_to_openmpi/bin/mpirun -np $NPROCESS --hostfile host.list
>>>>>>>> --mca
>>>>>>>>
>>>>>>>> btl self,sm,tcp --display-map --verbose --version --mca
>>>>>>>> mpi_warn_on_fork 0 --mca btl_openib_want_fork_support 0 [...]
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Eloi
>>>>>>
>>>>>> _______________________________________________
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