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microsoft / Microsoft-MPI

Microsoft MPI
MIT License
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Incomplete implementation of standards since MPI-2.0 #15

Open jedbrown opened 5 years ago

jedbrown commented 5 years ago

MPI-2.1 was published in 2008, but mpi.h still contains

#define MPI_VERSION     2
#define MPI_SUBVERSION 0

MS-MPI is portrayed at SC/MPI Forum meetings as merely lagging in MPI-3.1 implementation, but users who check the version macros get only MPI-2.0 (published in 2003). I realize that some functions from later standards are available, but these need to be tested individually if one wishes to use them while continuing to support MS-MPI.

It would be extremely valuable for the MPI community to understand whether conforming support for MPI-2.1 and later are planned, and if so, what the timeline may be.

jithinjosepkl commented 5 years ago

@jedbrown - The above slide indicates the what all MPI 3.1 features are supported in MS-MPI. I believe the reason for 2.0 as version in mpi.h is because not all features of later MPI standard versions are supported in MS-MPI.

I am not sure we have a planned timeline for later MPI standard versions. Now that MS-MPI is open-source, we are open to community participation in advancing MS-MPI.

jedbrown commented 5 years ago

It would be useful for MS-MPI to provide a comprehensive list of features that are missing relative to each MPI release after the presently supported 2.0 (i.e, 2.1, 2.2, 3.0, and 3.1). A lot of developers of MPI-based libraries do not develop on Windows, but would like their libraries to work with MS-MPI. MS-MPI is currently the most deficient vendor implementation in widespread use, and that imposes a significant cost on all these developers, either taking resources away from other activities or driving them to drop support for MS-MPI. A modest effort in documentation and clarity of ongoing development activities would go a long way.

jithinjosepkl commented 5 years ago

@jedbrown Completely with you on this, and definitely think a list of supported features will help the community. We'll work on this.

Btw, just fyi - one of our wish-list items is to move to CH4, which will enable most of the missing features. Just that we don't have a committed timeline for this yet.