Thanks a lot for posting my question. I am using Vampire Trace (VT) library for performance diagnosis and enhancement. An excerpted output of the code profiling using VT looks like the following table where the bottleneck process is named ‘sync’ (in the first row). I did not know or use a function ‘sync’ in my MPI code. Can someone tell me how ‘sync’ enters the context of an MPI code and how one may do to mitigate the related bottleneck problem? Thanks so much for help.






                                    excl. time  incl. time

*excl. time  incl. time      calls      / call      / call             name

    23.710s     23.710s          2       11.855s     11.855s        sync

     3.403s      3.403s          2            1.701s      1.701s          MPI_Barrier

     3.240s      3.269s          1            3.240s      3.269s         MPI_Init

     1.966s      1.966s         42        46.812ms    46.812ms  MPI_Waitall

     0.680s      0.680s    10.3125   65.932ms    65.932ms  MPI_Wait

     0.639s      0.639s          2           0.320s          0.320s     MPI_Allreduce

     0.403s      0.403s 806017.625     0.499us  0.499us  _ZN14CellTetLaminar6ddendzEi

     0.359s      0.359s 1134916.62     0.315us  0.315us  _2__STRING.244



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