Hi Ralph,
you are indeed correct. However, many of our users
have workstations such as me, with OpenMPI provided by installing a package.
So we don't know what has been configured.
Then we have failures, since, for instance, Ubuntu 14.04 by default appears
to have been built
with heterogeneous support! The other (working) machine is a large HPC, and
it seems OpenMPI was built
without heterogeneous support.
Currently we work around the problem for packing and unpacking by having a
compiler switch
that will switch between calls to pack/unpack_external and pac/unpack.
It is only now we started to track down what the problem actually is.
kindest regards
Mike
On 11 February 2016 at 15:54, Ralph Castain <r...@open-mpi.org> wrote:
> Out of curiosity: if both systems are Intel, they why are you enabling
> hetero? You don’t need it in that scenario.
>
> Admittedly, we do need to fix the bug - just trying to understand why you
> are configuring that way.
>
>
> On Feb 10, 2016, at 8:46 PM, Michael Rezny <michael.re...@monash.edu>
> wrote:
>
> Hi Gilles,
> I can confirm that with a fresh download and build from source for OpenMPI
> 1.10.2
> with --enable-heterogeneous
> the unpacked ints are the wrong endian.
>
> However, without --enable-heterogeneous, the unpacked ints are correct.
>
> So, this problem still exists in heterogeneous builds with OpenMPI version
> 1.10.2.
>
> kindest regards
> Mike
>
> On 11 February 2016 at 14:48, Gilles Gouaillardet <
> gilles.gouaillar...@gmail.com> wrote:
>
>> Michael,
>>
>> does your two systems have the same endianness ?
>>
>> do you know how openmpi was configure'd on both systems ?
>> (is --enable-heterogeneous enabled or disabled on both systems ?)
>>
>> fwiw, openmpi 1.6.5 is old now and no more maintained.
>> I strongly encourage you to use openmpi 1.10.2
>>
>> Cheers,
>>
>> Gilles
>>
>> On Thursday, February 11, 2016, Michael Rezny <michael.re...@monash.edu>
>> wrote:
>>
>>> Hi,
>>> I am running Ubuntu 14.04 LTS with OpenMPI 1.6.5 and gcc 4.8.4
>>>
>>> On a single rank program which just packs and unpacks two ints using
>>> MPI_Pack_external and MPI_Unpack_external
>>> the unpacked ints are in the wrong endian order.
>>>
>>> However, on a HPC, (not Ubuntu), using OpenMPI 1.6.5 and gcc 4.8.4 the
>>> unpacked ints are correct.
>>>
>>> Is it possible to get some assistance to track down what is going on?
>>>
>>> Here is the output from the program:
>>>
>>> ~/tests/mpi/Pack test1
>>> send data 000004d2 0000162e
>>> MPI_Pack_external: 0
>>> buffer size: 8
>>> MPI_unpack_external: 0
>>> recv data d2040000 2e160000
>>>
>>> And here is the source code:
>>>
>>> #include <stdio.h>
>>> #include <mpi.h>
>>>
>>> int main(int argc, char *argv[]) {
>>> int numRanks, myRank, error;
>>>
>>> int send_data[2] = {1234, 5678};
>>> int recv_data[2];
>>>
>>> MPI_Aint buffer_size = 1000;
>>> char buffer[buffer_size];
>>>
>>> MPI_Init(&argc, &argv);
>>> MPI_Comm_size(MPI_COMM_WORLD, &numRanks);
>>> MPI_Comm_rank(MPI_COMM_WORLD, &myRank);
>>>
>>> printf("send data %08x %08x \n", send_data[0], send_data[1]);
>>>
>>> MPI_Aint position = 0;
>>> error = MPI_Pack_external("external32", (void*) send_data, 2, MPI_INT,
>>> buffer, buffer_size, &position);
>>> printf("MPI_Pack_external: %d\n", error);
>>>
>>> printf("buffer size: %d\n", (int) position);
>>>
>>> position = 0;
>>> error = MPI_Unpack_external("external32", buffer, buffer_size,
>>> &position,
>>> recv_data, 2, MPI_INT);
>>> printf("MPI_unpack_external: %d\n", error);
>>>
>>> printf("recv data %08x %08x \n", recv_data[0], recv_data[1]);
>>>
>>> MPI_Finalize();
>>>
>>> return 0;
>>> }
>>>
>>>
>>>
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