It is not clear that passing MPI_INFO_NULL should result in resetting hints to default. For example, pg 248 at the bottom says "When an info object that specifies a subset of valid hints is passed to MPI_COMM_SET_INFO, there will be no effect on previously set or defaulted hints that the info does not specify." So if MPI_INFO_NULL is passed, at best nothing should happen. But the function definition doesn't say that INFO_NULL is a valid parameter. The behavior you are seeing is because comm_set_info uses a different (probably buggy) null test MPIR_ERRTEST_ARGNULL(info, "info", mpi_errno); whereas win_set_info uses MPIR_ERRTEST_INFO(info, mpi_errno); and I/O uses something else :-). Rajeev On Apr 9, 2014, at 4:51 AM, Lisandro Dalcin <[email protected]> wrote:

Right now, it success for Comm but fails for Win and File. IMHO, all should success, this should be a way for users to ask the implementation "please, reset the info hints to whatever the defaults are".

If you decide they should fail, then the Comm case needs a fix to generate an error.

$ mpicc comm_set_info.c $ ./a.out

$ mpicc win_set_info.c $ ./a.out Fatal error in MPI_Win_set_info: Invalid argument, error stack: MPI_Win_set_info(126): MPI_Win_set_info(win=win=0xa0000000, info=MPI_INFO_NULL) failed MPI_Win_set_info(82).: Null MPI_Info

$ mpicc file_set_info.c $ ./a.out Fatal error in PMPI_Info_dup: Invalid argument, error stack: PMPI_Info_dup(149): MPI_Info_dup(MPI_INFO_NULL, newinfo=0x7fff58b899c4) failed PMPI_Info_dup(108): Null MPI_Info

PS: Perhaps you have an easy fix for the error message (PMPI -> MPI) in the last one?

-- Lisandro Dalcin --------------- CIMEC (UNL/CONICET) Predio CONICET-Santa Fe Colectora RN 168 Km 472, Paraje El Pozo 3000 Santa Fe, Argentina Tel: +54-342-4511594 (ext 1016) Tel/Fax: +54-342-4511169 <comm_set_info.c><file_set_info.c><win_set_info.c>