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Subject: Re: [OMPI users] Segmentation fault when Send/Recv, onheterogeneouscluster (32/64 bit machines)
From: TRINH Minh Hieu (mhtrinh_at_[hidden])
Date: 2010-03-08 09:56:43


Hello,

I changed the test code (hetero.c, in attach) so that the master (where data
is centralized) can be rank 1 or 2.
I tested with a master,rank 2 or rank 1 : same probleme, when the master is
a 64bit machine, as soon as it receive data from a 32bit machines it got
segfault. no probleme with a 32bit master. It seems to not be rank dependent
...

Regards,

On Mon, Mar 8, 2010 at 1:27 PM, Terry Dontje <terry.dontje_at_[hidden]>wrote:

> We (Oracle) have not done that much extensive limits testing going between
> 32 to 64bit applications. Most of the testing we've done is more around
> endianess (SPARC vs x86_64).
>
> Though the below is kind of interesting. Sounds like the eager limit isn't
> being normalized on the 64 bit machines. Though a 32 bit rank 0 solving the
> problem also is very interesting, I wonder if that is not more due to which
> rank is send and receiving?
>
> --td
>
>
>
>> Message: 3
>> Date: Sun, 7 Mar 2010 05:34:21 -0600
>> From: "Jeff Squyres (jsquyres)" <jsquyres_at_[hidden]>
>> Subject: Re: [OMPI users] Segmentation fault when Send/Recv
>> onheterogeneouscluster (32/64 bit machines)
>> To: <users_at_[hidden]>
>> Message-ID:
>> <58D723FE08DC6A4398E6596E38F3FA1705670F_at_[hidden]>
>> Content-Type: text/plain; charset="utf-8"
>>
>> Ibm and sun (oracle) have probably done the most heterogeneous testing,
>> but its probably not as stable as our homogeneous code paths.
>>
>> Terry/brad - do you have any insight here?
>>
>> Yes, setting eager limit high can impact performance. Its the amount of
>> data that ompi will send eagerly without waiting for an ack from the
>> receiver. There are several secondary performance effects that can occur if
>> you are using sockets for transport and/or your program is only loosely
>> synchronized. If your prog is tightly synchronous, it may not have too huge
>> of an overall perf impact.
>> -jms
>> Sent from my PDA. No type good.
>>
>> ----- Original Message -----
>> From: users-bounces_at_[hidden] <users-bounces_at_[hidden]>
>> To: Open MPI Users <users_at_[hidden]>
>> Sent: Thu Mar 04 09:02:19 2010
>> Subject: Re: [OMPI users] Segmentation fault when Send/Recv
>> onheterogeneouscluster (32/64 bit machines)
>>
>> Hi,
>>
>> I have some new discovery about this problem :
>>
>> It seems that the array size sendable from a 32bit to 64bit machines
>> is proportional to the parameter "btl_tcp_eager_limit"
>> When I set it to 200 000 000 (2e08 bytes, about 190MB), I can send an
>> array up to 2e07 double (152MB).
>>
>> I didn't found much informations about btl_tcp_eager_limit other than
>> in the "ompi_info --all" command. If I let it at 2e08, will it impacts
>> the performance of OpenMPI ?
>>
>> It may be noteworth also that if the master (rank 0) is a 32bit
>> machines, I don't have segfault. I can send big array with small
>> "btl_tcp_eager_limit" from a 64bit machine to a 32bit one.
>>
>> Do I have to move this thread to devel mailing list ?
>>
>> Regards,
>>
>> TMHieu
>>
>> On Tue, Mar 2, 2010 at 2:54 PM, TRINH Minh Hieu <mhtrinh_at_[hidden]>
>> wrote:
>>
>>
>>> Hello,
>>>
>>> Yes, I compiled OpenMPI with --enable-heterogeneous. More precisely I
>>> compiled with :
>>> $ ./configure --prefix=/tmp/openmpi --enable-heterogeneous
>>> --enable-cxx-exceptions --enable-shared
>>> --enable-orterun-prefix-by-default
>>> $ make all install
>>>
>>> I attach the output of ompi_info of my 2 machines.
>>>
>>> ? ?TMHieu
>>>
>>> On Tue, Mar 2, 2010 at 1:57 PM, Jeff Squyres <jsquyres_at_[hidden]> wrote:
>>>
>>>
>>>> Did you configure Open MPI with --enable-heterogeneous?
>>>>
>>>> On Feb 28, 2010, at 1:22 PM, TRINH Minh Hieu wrote:
>>>>
>>>>
>>>>
>>>>> Hello,
>>>>>
>>>>> I have some problems running MPI on my heterogeneous cluster. More
>>>>> precisley i got segmentation fault when sending a large array (about
>>>>> 10000) of double from a i686 machine to a x86_64 machine. It does not
>>>>> happen with small array. Here is the send/recv code source (complete
>>>>> source is in attached file) :
>>>>> ========code ================
>>>>> ? ? if (me == 0 ) {
>>>>> ? ? ? ? for (int pe=1; pe<nprocs; pe++)
>>>>> ? ? ? ? {
>>>>> ? ? ? ? ? ? ? ? printf("Receiving from proc %d : ",pe); fflush(stdout);
>>>>> ? ? ? ? ? ? d=(double *)malloc(sizeof(double)*n);
>>>>> ? ? ? ? ? ? MPI_Recv(d,n,MPI_DOUBLE,pe,999,MPI_COMM_WORLD,&status);
>>>>> ? ? ? ? ? ? printf("OK\n"); fflush(stdout);
>>>>> ? ? ? ? }
>>>>> ? ? ? ? printf("All done.\n");
>>>>> ? ? }
>>>>> ? ? else {
>>>>> ? ? ? d=(double *)malloc(sizeof(double)*n);
>>>>> ? ? ? MPI_Send(d,n,MPI_DOUBLE,0,999,MPI_COMM_WORLD);
>>>>> ? ? }
>>>>> ======== code ================
>>>>>
>>>>> I got segmentation fault with n=10000 but no error with n=1000
>>>>> I have 2 machines :
>>>>> sbtn155 : Intel Xeon, ? ? ? ? x86_64
>>>>> sbtn211 : Intel Pentium 4, i686
>>>>>
>>>>> The code is compiled in x86_64 and i686 machine, using OpenMPI 1.4.1,
>>>>> installed in /tmp/openmpi :
>>>>> [mhtrinh_at_sbtn211 heterogenous]$ make hetero
>>>>> gcc -Wall -I. -std=c99 -O3 -I/tmp/openmpi/include -c hetero.c -o
>>>>> hetero.i686.o
>>>>> /tmp/openmpi/bin/mpicc -Wall -I. -std=c99 -O3 -I/tmp/openmpi/include
>>>>> hetero.i686.o -o hetero.i686 -lm
>>>>>
>>>>> [mhtrinh_at_sbtn155 heterogenous]$ make hetero
>>>>> gcc -Wall -I. -std=c99 -O3 -I/tmp/openmpi/include -c hetero.c -o
>>>>> hetero.x86_64.o
>>>>> /tmp/openmpi/bin/mpicc -Wall -I. -std=c99 -O3 -I/tmp/openmpi/include
>>>>> hetero.x86_64.o -o hetero.x86_64 -lm
>>>>>
>>>>> I run with the code using appfile and got thoses error :
>>>>> $ cat appfile
>>>>> --host sbtn155 -np 1 hetero.x86_64
>>>>> --host sbtn155 -np 1 hetero.x86_64
>>>>> --host sbtn211 -np 1 hetero.i686
>>>>>
>>>>> $ mpirun -hetero --app appfile
>>>>> Input array length :
>>>>> 10000
>>>>> Receiving from proc 1 : OK
>>>>> Receiving from proc 2 : [sbtn155:26386] *** Process received signal ***
>>>>> [sbtn155:26386] Signal: Segmentation fault (11)
>>>>> [sbtn155:26386] Signal code: Address not mapped (1)
>>>>> [sbtn155:26386] Failing at address: 0x200627bd8
>>>>> [sbtn155:26386] [ 0] /lib64/libpthread.so.0 [0x3fa4e0e540]
>>>>> [sbtn155:26386] [ 1] /tmp/openmpi/lib/openmpi/mca_pml_ob1.so
>>>>> [0x2aaaad8d7908]
>>>>> [sbtn155:26386] [ 2] /tmp/openmpi/lib/openmpi/mca_btl_tcp.so
>>>>> [0x2aaaae2fc6e3]
>>>>> [sbtn155:26386] [ 3] /tmp/openmpi/lib/libopen-pal.so.0 [0x2aaaaafe39db]
>>>>> [sbtn155:26386] [ 4]
>>>>> /tmp/openmpi/lib/libopen-pal.so.0(opal_progress+0x9e) [0x2aaaaafd8b9e]
>>>>> [sbtn155:26386] [ 5] /tmp/openmpi/lib/openmpi/mca_pml_ob1.so
>>>>> [0x2aaaad8d4b25]
>>>>> [sbtn155:26386] [ 6] /tmp/openmpi/lib/libmpi.so.0(MPI_Recv+0x13b)
>>>>> [0x2aaaaab30f9b]
>>>>> [sbtn155:26386] [ 7] hetero.x86_64(main+0xde) [0x400cbe]
>>>>> [sbtn155:26386] [ 8] /lib64/libc.so.6(__libc_start_main+0xf4)
>>>>> [0x3fa421e074]
>>>>> [sbtn155:26386] [ 9] hetero.x86_64 [0x400b29]
>>>>> [sbtn155:26386] *** End of error message ***
>>>>>
>>>>> --------------------------------------------------------------------------
>>>>> mpirun noticed that process rank 0 with PID 26386 on node sbtn155
>>>>> exited on signal 11 (Segmentation fault).
>>>>>
>>>>> --------------------------------------------------------------------------
>>>>>
>>>>> Am I missing an option in order to run in heterogenous cluster ?
>>>>> MPI_Send/Recv have limit array size when using heterogeneous cluster ?
>>>>> Thanks for your help. Regards
>>>>>
>>>>> --
>>>>> ============================================
>>>>> ? ?M. TRINH Minh Hieu
>>>>> ? ?CEA, IBEB, SBTN/LIRM,
>>>>> ? ?F-30207 Bagnols-sur-C?ze, FRANCE
>>>>> ============================================
>>>>>
>>>>> <hetero.c.bz2>_______________________________________________
>>>>> users mailing list
>>>>> users_at_[hidden]
>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>>
>>>>>
>>>> --
>>>> Jeff Squyres
>>>> jsquyres_at_[hidden]
>>>> For corporate legal information go to:
>>>> http://www.cisco.com/web/about/doing_business/legal/cri/
>>>>
>>>>
>>>> _______________________________________________
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>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>
>>>>
>>>
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-- 
============================================
  M. TRINH Minh Hieu
  CEA, IBEB, SBTN/LIRM,
  F-30207 Bagnols-sur-Cèze, FRANCE
============================================