The call of MPI_Allgatherv with sendbuf and sendtype parameters equal to MPI_IN_PLACE and NULL correspondingly, produces the segmentation fault.
The problem is that sendtype is used even when sendbuf value is MPI_IN_PLACE. But according to the standard, sendtype and sendcount parameters should be ignored in this case.
Signed-off-by: Mikhail Kurnosov <mkurnosov@gmail.com>
As we changed the ABI (forcing a major release), we can limit
the size of the predefined communicators by moving the collective
structure outside the communicator. This might have a minimal,
but unnoticeable, impact on performance. This approach has been
discussed during the January 2017 devel meeting.
Signed-off-by: George Bosilca <bosilca@icl.utk.edu>
Signed-off-by: Joshua Hursey <jhursey@us.ibm.com>
MPI_Allgatherv with MPI_IN_PLACE reads data from wrong location.
They were locating the MPI_IN_PLACE send buffer as
```c
send_buf = (char*)rbuf;
for (i = 0; i < rank; ++i) {
send_buf += ((ptrdiff_t)rcounts[i] * extent);
}
```
when it should be
```c
send_buf = (char*)rbuf;
send_buf += ((ptrdiff_t)disps[rank] * extent);
```
because disps[] specifies where things are in the v-style buffers.
Signed-off-by: Joshua Hursey <jhursey@us.ibm.com>
