On , 2021Aug21, at 14:08, Victor Eijkhout 
<[email protected]<mailto:[email protected]>> wrote:

3b. Dup and free million times takes more time than writing this email. Why do 
I keep hearing that OpenMPI is so great? Everything slightly non-standard I try 
is hopelessly slow and broken.

Partial rehabilitation for OpenMPI:

Finished dup/free'ing 1000000 communicators

real    0m9.301s
user    0m9.120s
sys     0m0.114s

So that’s only 4 times slower than Mvapich, but the ludicrously slow 
performance is only for Spectrum MPI, not OpenMPI per se.

Victor.

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