On Tue, Jul 16, 2013 at 11:03:27PM +0200, George Bosilca wrote: > > On Jul 16, 2013, at 22:29 , Jeff Squyres (jsquyres) <jsquy...@cisco.com> > wrote: > > > On Jul 16, 2013, at 4:22 PM, George Bosilca <bosi...@icl.utk.edu> wrote: > > > >> Btw, I have a question to you fellow MPI Forum attendees. I just can't > >> remember why the MPI forum felt there was a need for the > >> MPI_Type_get[_true]_extent_x? MPI_Count can't be bigger than MPI_Aint, > > > > Yes, it can -- it has to be the largest integer type (i.e., it even has to > > be able to handle an MPI_Offset). > > Technicalities! In the entire standard MPI_Offset is only used to access > files, not to build datatypes. As such there is no way to have the extent of > an datatype bigger than MPI_Aint. Thus, these accessors returning MPI_Count > are a useless overkill, as they cannot offer more precision that what the > version returning MPI_Aint is already offering. > > George. > > PS: I hope nobody has the idea to define the MPI_Offset as a signed type ?
Externally MPI_Offset is defines as a signed type (long long, long, or int) but internally it is treated as unsigned. I will update MPI_Count to have the same treatment (since it can be MPI_UNDEFINED which is a negative number). -Nathan
