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MPI shared communication with slided access




I have two questions regarding using mpi shared memory communication



1) If I have a MPI rank which is the only one that writes to a window, is it necessary to employ mpi_win_lock, and mpi_win_unlock?
I know that my application would never have others trying to write to that window. They only read the content of the window, and I make sure that they read after a MPI_BARRIER, so the content of the window has been updated.



2) In my application I have one MPI rank, which allocates a shared window that needs to be read by 1:N other MPI ranks.

MPI rank 1 shall only read: rma(1:10) 

MPI rank 2 shall only read rma(11:20) 

MPI rank N shall only read  rma(10*(N-1)+1:10*N)

Currently, all 1 to N ranks  are querying the whole shared window, i.e. the size "10*N" with MPI_WIN_SHARED_QUERY.


I am asking if it is possible to apply the MPI_WIN_SHARED_QUERY function such that MPI rank 1 only can access the window from 1:10 and rank 2 from 11:20 etc.

In this way, each rank has a local accessing from 1:10 but they refer to different chunks of the shared window? Is this possible?



Thanks very much!

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