Michael,
I think it is worst than that ...
without --enable-heterogeneous, it seems the data is not
correctly packed
(e.g. it is not converted to big endian), at least on a x86_64 arch.
unpack looks broken too, but pack followed by unpack does work.
that means if you are reading data correctly written in
external32e format,
it will not be correctly unpacked.
with --enable-heterogeneous, it is only half broken
(I do not know yet whether pack or unpack is broken ...)
and pack followed by unpack does not work.
I will double check that tomorrow
Cheers,
Gilles
On Thursday, February 11, 2016, Michael Rezny
<michael.re...@monash.edu
<javascript:_e(%7B%7D,'cvml','michael.re...@monash.edu');>> wrote:
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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