On 9/15/23 03:17, timo Hyvärinen wrote:
So here is my question, which tutorial steps demonstrate how to implement the
mpi-thread hybrid parallelism. I've found step-48 is talking about this, but
I wonder are there any other tutorial programs to look at? I also wonder if
any of you guys have suggestions about mpi+thread parallelism under
dealii framework?
Timo:
If your code already works, then the usual suggestion would be to use one MPI
process per core, and to not use thread-parallelism at all. In that case, you
should be using all cores equally.
There is an often-repeated observation that one can not optimize a code
without first profiling it. From your question, it sounds like you are not
entire sure why assembly is taking so long. I think it is likely that whatever
solution you try will not be successful unless you first find out why it
really is taking this long. I would run the code on one MPI process first and
see whether assembly is taking 99% there as well. If that's the case, use
valgrind's callgrind to figure out why. If it's not taking 99% on one MPI
process, then you've got another riddle to solve.
Best
W.
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Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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