Thanks. That's a bug in your code. In mcs-lock-fop.c:92, before you do an accumulate to notify the next rank, you need to reset your lmem[nextRank] back to -1. Otherwise, in the next iteration, you'll think that the value is set even if it is not. You can either do it using a local store followed by an MPI_WIN_SYNC or using MPI_Put or MPI_Accumulate. After that fix your program seems to work correctly. I also found that it was not a bug in the MPI implementation, after all. Even without the MODE_NOCHECK hint, the program seems to work correctly now. Nevertheless, this is a good regression test to have and we'd like to include it in our test harness. Would you mind providing this as a contribution to mpich? You'd need to sign the contributors' agreement for it: http://www.mpich.org/documentation/contributor-docs/ FWIW, here's the new code that includes the send/recv optimization that I pointed out in my previous email. Thanks, -- Pavan

On Mar 14, 2017, at 2:03 PM, Ask Jakobsen <[email protected]> wrote:

$ mpicc -Wall main.c mcs-lock-fop.c

$ while true; do mpiexec -n 2 ./a.out ; done

At some point it does locks up.

On Tue, Mar 14, 2017 at 7:52 PM, Balaji, Pavan <[email protected]> wrote:

Thanks. I can't seem to reproduce the deadlock anymore after the MODE_NOCHECK hint. Can you tell us how to reproduce it?

-- Pavan

...

On Mar 14, 2017, at 1:43 PM, Ask Jakobsen <[email protected]> wrote:

Sorry, now header file is attached.

On Tue, Mar 14, 2017 at 5:11 PM, Balaji, Pavan <[email protected]> wrote:

...

On Mar 14, 2017, at 4:58 AM, Ask Jakobsen <[email protected]> wrote: The MPI_Fetch_and_op version trying to implement Pavan's ideas as I understand it (no async progress necessary, but also tested with it enabled).

The header file is missing.

-- Pavan

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