Thanks, Gilles.
We are addressing this.
Josh
Sent from my iPhone
> On Jun 25, 2015, at 11:03 AM, Gilles Gouaillardet <gil...@rist.or.jp> wrote:
>
> Folks,
>
> this is a followup on an issue reported by Daniel on the users mailing list :
> OpenMPI is built with hcoll from Mellanox.
> the coll ml module has default priority zero.
>
> on my cluster, it works just fine
> on Daniel's cluster, it crashes.
>
> i was able to reproduce the crash by tweaking mca_base_component_path and
> ensure
> the coll ml module is loaded first.
>
> basically, i found two issues :
> 1) libhcoll.so (vendor lib provided by Mellanox, i tested
> hpcx-v1.3.336-gcc-OFED-1.5.4.1-redhat6.2-x86_64) seems to include its own
> coll ml, since there are some *public* symbols that are common to this module
> (ml_open, ml_coll_hier_barrier_setup, ...)
> 2) coll ml priority is zero, and even if the library is dlclose'd, it seems
> this is uneffective
> (nothing changed in /proc/xxx/maps before and after dlclose)
>
>
> there are two workarounds :
> mpirun --mca coll ^ml
> or
> mpirun --mca coll ^hcoll ... (probably not what is needed though ...)
>
> is it expected the library is not unloaded after dlclose ?
>
> Mellanox folks,
> can you please double check how libhcoll is built ?
> i guess it would work if the ml_ symbols were private to the library.
> if not, the only workaround is to mpirun --mca coll ^ml
> otherwise, it might crash (if coll_ml is loaded before coll_hcoll, which is
> really system dependent)
>
> Cheers,
>
> Gilles
>> On 6/25/2015 10:46 AM, Gilles Gouaillardet wrote:
>> Daniel,
>>
>> thanks for the logs.
>>
>> an other workaround is to
>> mpirun --mca coll ^hcoll ...
>>
>> i was able to reproduce the issue, and it surprisingly occurs only if the
>> coll_ml module is loaded *before* the hcoll module.
>> /* this is not the case on my system, so i had to hack my
>> mca_base_component_path in order to reproduce the issue */
>>
>> as far as i understand, libhcoll is a proprietary software, so i cannot dig
>> into it.
>> that being said, i noticed libhcoll defines some symbols (such as
>> ml_coll_hier_barrier_setup) that are also defined by the coll_ml module, so
>> it is likely hcoll coll_ml and openmpi coll_ml are not binary compatible
>> hence the error.
>>
>> i will dig a bit more and see if this is even supposed to happen (since
>> coll_ml_priority is zero, why is the module still loaded ?)
>>
>> as far as i am concerned, you *have to* mpirun --mca coll ^ml or
>> update your user/system wide config file to blacklist the coll_ml module to
>> ensure this is working.
>>
>> Mike and Mellanox folks, could you please comment on that ?
>>
>> Cheers,
>>
>> Gilles
>>
>>
>>
>>> On 6/24/2015 5:23 PM, Daniel Letai wrote:
>>> Gilles,
>>>
>>> Attached the two output logs.
>>>
>>> Thanks,
>>> Daniel
>>>
>>>> On 06/22/2015 08:08 AM, Gilles Gouaillardet wrote:
>>>> Daniel,
>>>>
>>>> i double checked this and i cannot make any sense with these logs.
>>>>
>>>> if coll_ml_priority is zero, then i do not any way how
>>>> ml_coll_hier_barrier_setup can be invoked.
>>>>
>>>> could you please run again with --mca coll_base_verbose 100
>>>> with and without --mca coll ^ml
>>>>
>>>> Cheers,
>>>>
>>>> Gilles
>>>>
>>>>> On 6/22/2015 12:08 AM, Gilles Gouaillardet wrote:
>>>>> Daniel,
>>>>>
>>>>> ok, thanks
>>>>>
>>>>> it seems that even if priority is zero, some code gets executed
>>>>> I will confirm this tomorrow and send you a patch to work around the
>>>>> issue if that if my guess is proven right
>>>>>
>>>>> Cheers,
>>>>>
>>>>> Gilles
>>>>>
>>>>>> On Sunday, June 21, 2015, Daniel Letai <d...@letai.org.il> wrote:
>>>>>> MCA coll: parameter "coll_ml_priority" (current value: "0", data source:
>>>>>> default, level: 9 dev/all, type: int)
>>>>>>
>>>>>> Not sure how to read this, but for any n>1 mpirun only works with --mca
>>>>>> coll ^ml
>>>>>>
>>>>>> Thanks for helping
>>>>>>
>>>>>>> On 06/18/2015 04:36 PM, Gilles Gouaillardet wrote:
>>>>>>> This is really odd...
>>>>>>>
>>>>>>> you can run
>>>>>>> ompi_info --all
>>>>>>> and search coll_ml_priority
>>>>>>>
>>>>>>> it will display the current value and the origin
>>>>>>> (e.g. default, system wide config, user config, cli, environment
>>>>>>> variable)
>>>>>>>
>>>>>>> Cheers,
>>>>>>>
>>>>>>> Gilles
>>>>>>>
>>>>>>>> On Thursday, June 18, 2015, Daniel Letai <d...@letai.org.il> wrote:
>>>>>>>> No, that's the issue.
>>>>>>>> I had to disable it to get things working.
>>>>>>>>
>>>>>>>> That's why I included my config settings - I couldn't figure out which
>>>>>>>> option enabled it, so I could remove it from the configuration...
>>>>>>>>
>>>>>>>>> On 06/18/2015 02:43 PM, Gilles Gouaillardet wrote:
>>>>>>>>> Daniel,
>>>>>>>>>
>>>>>>>>> ML module is not ready for production and is disabled by default.
>>>>>>>>>
>>>>>>>>> Did you explicitly enable this module ?
>>>>>>>>> If yes, I encourage you to disable it
>>>>>>>>>
>>>>>>>>> Cheers,
>>>>>>>>>
>>>>>>>>> Gilles
>>>>>>>>>
>>>>>>>>>> On Thursday, June 18, 2015, Daniel Letai
>>>>>>>>>> <d...@letai.org.il> wrote:
>>>>>>>>>> given a simple hello.c:
>>>>>>>>>>
>>>>>>>>>> #include <stdio.h>
>>>>>>>>>> #include <mpi.h>
>>>>>>>>>>
>>>>>>>>>> int main(int argc, char* argv[])
>>>>>>>>>> {
>>>>>>>>>> int size, rank, len;
>>>>>>>>>> char name[MPI_MAX_PROCESSOR_NAME];
>>>>>>>>>>
>>>>>>>>>> MPI_Init(&argc, &argv);
>>>>>>>>>> MPI_Comm_size(MPI_COMM_WORLD, &size);
>>>>>>>>>> MPI_Comm_rank(MPI_COMM_WORLD, &rank);
>>>>>>>>>> MPI_Get_processor_name(name, &len);
>>>>>>>>>>
>>>>>>>>>> printf("%s: Process %d out of %d\n", name, rank, size);
>>>>>>>>>>
>>>>>>>>>> MPI_Finalize();ffff
>>>>>>>>>> }
>>>>>>>>>>
>>>>>>>>>> for n=1
>>>>>>>>>> mpirun -n 1 ./hello
>>>>>>>>>> it works correctly.
>>>>>>>>>>
>>>>>>>>>> for n>1 it segfaults with signal 11
>>>>>>>>>> used gdb to trace the problem to ml coll:
>>>>>>>>>>
>>>>>>>>>> Program received signal SIGSEGV, Segmentation fault.
>>>>>>>>>> 0x00007ffff6750845 in ml_coll_hier_barrier_setup()
>>>>>>>>>> from <path to openmpi 1.8.5>/lib/openmpi/mca_coll_ml.so
>>>>>>>>>>
>>>>>>>>>> running with
>>>>>>>>>> mpirun -n 2 --mca coll ^ml ./hello
>>>>>>>>>> works correctly
>>>>>>>>>>
>>>>>>>>>> using mellanox ofed 2.3-2.0.5-rhel6.4-x86_64, if it's at all
>>>>>>>>>> relevant.
>>>>>>>>>> openmpi 1.8.5 was built with following options:
>>>>>>>>>> rpmbuild --rebuild --define 'configure_options --with-verbs=/usr
>>>>>>>>>> --with-verbs-libdir=/usr/lib64 CC=gcc CXX=g++ FC=gfortran CFLAGS="-g
>>>>>>>>>> -O3" --enable-mpirun-prefix-by-default
>>>>>>>>>> --enable-orterun-prefix-by-default --disable-debug
>>>>>>>>>> --with-knem=/opt/knem-1.1.1.90mlnx --with-platform=optimized
>>>>>>>>>> --without-mpi-param-check --with-contrib-vt-flags=--disable-iotrace
>>>>>>>>>> --enable-builtin-atomics --enable-cxx-exceptions
>>>>>>>>>> --enable-sparse-groups --enable-mpi-thread-multiple
>>>>>>>>>> --enable-memchecker --enable-btl-openib-failover
>>>>>>>>>> --with-hwloc=internal --with-verbs --with-x --with-slurm
>>>>>>>>>> --with-pmi=/opt/slurm --with-fca=/opt/mellanox/fca
>>>>>>>>>> --with-mxm=/opt/mellanox/mxm --with-hcoll=/opt/mellanox/hcoll'
>>>>>>>>>> openmpi-1.8.5-1.src.rpm
>>>>>>>>>>
>>>>>>>>>> gcc version 5.1.1
>>>>>>>>>>
>>>>>>>>>> Thanks in advance
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>>>>>>>>>
>>>>>>>>>
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