Hi Kenneth, I have added a command to print the linking info for the benchmark executable for each mpi build as per [1]. The results for benchmarks built with mpich@develop with [email protected] are here [2] where the mpi_config file [3] has the ldd info printed out and I’m confirming that the right mpi library is being used. I don’t see any hcoll linking and can confirm that it is picking up the right mpich version. I have also printed out the linking info for mpich itself and attach the output of the following along with this email : [sas4990@quser10 ~]$ ldd $(spack location -i mpich@develop%[email protected])/lib/libmpich.so &> mpich_ldd The only thing that I’m concerned about is that the libmpich.so has no link to libslurmfull.so (but openmpi does link to). Thank You, Sajid Ali | PhD Candidate Applied Physics Northwestern University s-sajid-ali.github.io