Prior to this commit, PnetCDF wraps each MPI read/write call in put/get APIs with two MPI_File_set_view(). One is before the MPI read/write call to take advantage of MPI's fileview feature for accessing non-contiguous file locations. The other is after the MPI read/write call to make the whole file visible, as the root process may write to file header later in the data mode and it alone cannot make a call to MPI_File_set_view() because the function is collective.

In this commit, the second MPI_File_set_view() has been removed. The root process's fileview is changed to always keep the whole file header visible. Saving a collective call to MPI_File_set_view() is expected to improve some performance.


git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1926 c368ceb8-fd28-0410-a457-e46ee1d7cd4a
revert the change in r1926: add back -s

git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1927 c368ceb8-fd28-0410-a457-e46ee1d7cd4a
revise comments

git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1928 c368ceb8-fd28-0410-a457-e46ee1d7cd4a