[MPICH] about MPI_Reduce

[Thomas Moschny]

llwaeva at 21cn.com wrote:
> Thank you so much. The problem is solved. However, according to the
> problem, does it mean that no matter what kind of datatype I specified
> in MPI_Reduce, the whole buffer will be sent and received?

No, I don't think so. When sending and receiving buffers using datatypes
with holes in them, the bytes within the wholes should not be read or
sent over the network and must not be written to.
This holds for any communication operation in MPI.

- Thomas