On Thu, Jan 14, 2016 at 7:49 PM, Jeff Hammond <jeff.scie...@gmail.com> wrote:
> > > On Thu, Jan 14, 2016 at 3:05 PM, George Bosilca <bosi...@icl.utk.edu> > wrote: > >> >> On Jan 13, 2016, at 19:57 , Jim Edwards <jedwa...@ucar.edu> wrote: >> >> George and all. >> >> Back to OpenMPI, now the question is : >> >> “Is OpenMPI going to be updated (and when) in order to support an >> intuitive and user friendly feature, that is currently explicitly >> prohibited by the MPI 3.1 standard, but that might be part of the MPI-4 >> standard and that we already know is not backward compatible (*) ? >> >> >> If the MPI Forum agrees to amend the standard to allow this [currently >> forbidden] behavior, we will be bound to adapt. Meanwhile, I would assume >> that with regard to this particular question the MPICH implementation is >> far too user-friendly and only loosely standard compliant. >> > > > The MPI standard does not require implementations to catch ANY invalid > usage errors, so MPICH compliance is in no way affected by allowing invalid > usage. The error in question is completely innocuous and there is no value > whatsoever to crashing a user application over it. > That certainly a way of seeing it. In which case set your mpi_param_check to zero and let's close this discussion. > If you want to hop on the standard-compliance soapbox, let's start with > MPI-2 features like MPI_THREAD_MULTIPLE and RMA ;-) > > >> (*) fwiw, mpich already “implements" this, so backward incompatibility >> would only affect tools currently working with OpenMPI but not with mpich." >> >> i am a pragmatic guy, so i'd rather go for it, but here is what i am >> gonna do : >> >> unless George vetoes that, i will add this topic to the weekly call >> agenda, and wait for the community to make a decision >> (e.g. go / no go, and milestone if needed 1.10 series ? 2.0 ? 2.1 ? >> master only ?) >> >> >> A pragmatic user will certainly appreciate in all circumstances to type >> less characters (MPI_BYTE) instead of MPI_DATATYPE_NULL when used in >> combination with a statically known count of 0. >> >> > What is the type of NULL and nullptr? > Both because of static analysis and inferring MPI datatypes from pointer > types (as done in C++ codes), I'm not sure it's a good idea to say that > null buffers have a well-defined MPI type. > I fail to see the missing link between null pointers and MPI datatype, especially in the case you promote where you call an MPI function with a count of zero. Moreover, as mentioned by Bill on the MPI Forum mailing list, NULL is a valid buffer for MPI functions, even when the count is not ZERO when paired with the right datatype. My point in that this is a matter for the MPI Forum, all discussion outside that context are bound to be lost. George. > > Jeff > > >> Cheers, >> George. >> >> >> >> Cheers, >> >> Gilles >> >> >> >> _______________________________________________ >> users mailing list >> us...@open-mpi.org >> Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users >> Link to this post: >> http://www.open-mpi.org/community/lists/users/2016/01/28277.php >> > > > > -- > Jeff Hammond > jeff.scie...@gmail.com > http://jeffhammond.github.io/ > > _______________________________________________ > users mailing list > us...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: > http://www.open-mpi.org/community/lists/users/2016/01/28278.php >
