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Hi MPICH developers,
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<div class="">There is a pending PR on GitHub, <a href="https://github.com/pmodels/mpich/pull/4214" class="">https://github.com/pmodels/mpich/pull/4214</a>, that is proposing adding a new device layer API for ch4 — MPID_Pre_init. </div>
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<div class="">The current ADI a single MPID_Init(int *argc, int **argv, int required_thread_level, int *provided_thread_level). It parses command line argument and decides the thread_level among other device layer initializations. There are MPIR-layer initializations
both before MPID_Init that need know the thread-level. Even inside MPID_Init, different components may need know thread_level but it is not certain at which point the thread-level is determined. Currently, in MPIR_Init_thread, we initializes with a thread-level
based on user argument, which potentially will get changed by MPID_Init. That creates a potential inconsistency and as well as complications.</div>
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<div class="">The PR addresses it by splitting the argument parsing part of init into MPID_Pre_Init, that is called the very first thing during the init process, guaranteeing the thread-level that each components sees is the reliable final thread-level.</div>
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<div class="">While addressing the thread-level support is the motivation, once the MPID_Pre_init API is there, it will allow more flexible device initializations as well. </div>
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<div class="">The PR has already went through internal reviews and is ready to be merged. We welcome any comments.</div>
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— </div>
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Hui Zhou</div>
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