MPI_File_read_shared / MPI_File_write_shared on NFS seems to be very slow when running on multi-node environment compared to a single node run. originally detected with the mpich test case (*writeshf90*) Here is a minimal reproducer with MPI_File_read_shared, https://gist.github.com/AboorvaDevarajan/db4797e02ac71f60384a8254ae2862c8 [aboorvad@c712f6n06 io]$ cat hostfile_mpich c712f6n06:2 c712f6n07:2 [aboorvad@c712f6n06 io]$ time mpirun -np 4 --hostfile hostfile_mpich ./read_shared *real 0m14.709s* user 0m27.703s sys 0m1.438s [aboorvad@c712f6n06 io]$ time mpirun -np 4 ./read_shared *real 0m0.247s* user 0m0.153s sys 0m0.616s Is it an expected behaviour? If yes, why? Thanks. _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss