[mpich-discuss] PMI 2 deprecation in MPICH 5.0.0

[Felip Moll]

Hello,

MPICH 5.0.0 has been released, and the release notes announces that PMI 2 is now deprecated, and recommends switching to PMI 1.
It also says PMI 1 upgraded to PMI 1.2. Looking at some commits I also see that new features will be added to PMI 1.

I would like to understand the technical reasons behind deprecating PMI 2, as theorically it had a better startup latency, improved KVS, and so on compared to PMI 1 [1]
I understand that PMIx should be more appropriate than PMI 2 for large scale apps and this would probably be a reason to reduce efforts on supporting other PMIs, but why keep PMI1 and not PMI2?
Where does PMI 2 stand at that point?

Thank you!.

[1] PMI: A Scalable Parallel Process-Management Interface for Extreme-Scale Systems<https://www.mcs.anl.gov/papers/P1760.pdf >



Felip Moll
Slurm Sr Engineer
NVIDIA<https://urldefense.com/v3/__http:/www.nvidia.com/__;!!LpKI!m1it1uHwfgYmHS7qqdmJTPaSuMjYIFnhWAJLp5E9tO7nEVWPj3sTumZmbxBYOeHVOQS3q-Fgw_v2SqibGpA$ > [nvidia.com]<https://urldefense.com/v3/__http:/www.nvidia.com/__;!!LpKI!m1it1uHwfgYmHS7qqdmJTPaSuMjYIFnhWAJLp5E9tO7nEVWPj3sTumZmbxBYOeHVOQS3q-Fgw_v2SqibGpA$ >

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