Hello Gilles,
some comments interspersed
On 11/06/2015 02:50 PM, Gilles Gouaillardet wrote:
Harald,
the answer is in ompi/mca/coll/libnbc/nbc_ibcast.c
this has been revamped (but not 100%) in v2.x
(e.g. no more calls to MPI_Comm_{size,rank} but MPI_Type_size is still
being invoked)
Ah! it is interesting to know this pointer, thanks. Looks like others
such as igather and ireduce also have this issue :S
I will review this.
basically, no MPI_* should be invoked internally (e.g. we should use the
internal ompi_* or the PMPI_* symbol.
there is currently no plan for a v1.10.2 release, so you have to wait
for the v2.0.0)
Is it possible to know when this behavior was introduced? Maybe since
the first MPI3 implementation (was it OpenMPI 1.8?).
note you should wrap the C bindings (with a C library) and the Fortran
bindings (with a Fortran library).
currently, the fortran wrapper will likely invoke the C wrapper, but
that will no more be the case from v2.x
Oh! That's a pity. We usually use the LD_PRELOAD technique to inject the
instrumentation and since fortran wrapper invokes the C wrapper, we can
instrument either fortran or C applications with a single
instrumentation library. Other MPI implementations (I won't say names
here) also have this C/Fortran "separation", which requires us to
generate two instrumentation libraries, one for C and another for
Fortran apps.
Thank you!
Cheers,
Gilles
On Friday, November 6, 2015, Harald Servat <harald.ser...@bsc.es
<mailto:harald.ser...@bsc.es>> wrote:
Dear all,
we develop an instrumentation package based on PMPI and we've
observed that PMPI_Ibarrier and PMPI_Ibcast invoke regular
MPI_Comm_size and MPI_Comm_rank instead to the PMPI symbols (i.e.
PMPI_Comm_size and PMPI_Comm_rank) in OpenMPI 1.10.0.
I have attached simple example that demonstrates it when using
OpenMPI 1.10.0. The example creates a library (libinstrument) that
hooks MPI_Comm_size, MPI_Comm_rank and MPI_Ibarrier. Then, there's a
single MPI application that executes MPI_Ibarrier and waits for it.
The result when combining this binary with the instrumentation
library is the following:
# ~/aplic/openmpi/1.10.0/bin/mpirun -np 1 ./main
entering MPI_Ibarrier
entering MPI_Comm_rank
leaving MPI_Comm_rank
entering MPI_Comm_size
leaving MPI_Comm_size
leaving MPI_Ibarrier
which shows that MPI_Comm_rank and MPI_Comm_size are invoked
within MPI_Ibarrier.
I looked into ompi/mpi/ibarrier.c and
./ompi/mpi/c/profile/pibarrier.c but it wasn't evident to me what
might be wrong.
Can anyone check this? And if this could also occur to other MPI3
immediate collectives (MPI_Ireduce, MPI_Iallreduce, MPI_Igather, ...).
Thank you!
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