MS-MPI 10.0.12 with Orca RRS feed

  • Question

  • Hi,

    i have a problem with parallel computing on MS-MPI. I am using a quantum chemistry calculation programm called Orca. For my version of orca the MS-MPI version 10.0.124958.5 is recommend. 

    So here is my problem. I can get Orca to use MPI by including some keyword in my input file. The programm itself will then communicate with MS-MPI. This works great and is recommend and used by all windowsian orca users. The problem i have is, that if i want to use 100% of my cpu's, (I got four kernels  by the way), by adding in the input file "4", the cpu usage caps a 63% . Even if i add more kernels in the input file, the overall cpu usage caps again at 63%.

    Is there some way to remove this cap? Cause on my linux system its works quite well with 100% and the same input.

    Thank you for your help.

    Sunday, April 5, 2020 9:40 AM

All replies

  • Hello,

    It is very unlikely that not ideal CPU usage is caused by msmpi. Probably the Linux and Windows versions of the software are written differently, which causes the difference in CPU utilization. Is there a significant difference in execution time for the same input on Windows and Linux? That would be more indicative. One tip to improve Windows mpi performance is to pass "-affinity" command line argument to mpiexec. For more detailed analysis of performance on Windows you can use xperf.

    -thanks, Anna 

    Friday, April 17, 2020 5:04 PM