FLASH-IO: set hint romio_ds_write to disable

Set hint romio_no_indep_rw according to command-line option -i

Author: wkliao

benchmarks/FLASH-IO/checkpoint_ncmpi_parallel.F90

@@ -334,11 +334,17 @@ double precision function checkpoint_wr_ncmpi_par (filenum, simtime)
       filename = trim(basenm) // 'ncmpi_chk_'//fnum_string//'.nc'
 
       ! set up MPI I/O hints for performance enhancement
-      file_info = MPI_INFO_NULL
       call MPI_Info_create(file_info, err)
 
-      ! set some ROMIO hints
-      ! call MPI_Info_set(file_info, 'romio_no_indep_rw', 'true', err)
+      ! whether doing independent or collective writes
+      if (indep_io) then
+          call MPI_Info_set(file_info, 'romio_no_indep_rw', 'false', err)
+      else
+          call MPI_Info_set(file_info, 'romio_no_indep_rw', 'true', err)
+      endif
+
+      ! disable data sieving, as FLASH-IO does large continuous writes
+      call MPI_Info_set(file_info, "romio_ds_write", "disable", err)
 
       ! disable file offset alignment for fixed-size variables
       call MPI_Info_set(file_info, "nc_var_align_size", "1", err)

benchmarks/FLASH-IO/plotfile_ncmpi_parallel.F90

@@ -372,11 +372,17 @@ double precision function plotfile_ncmpi_par(filenum, simtime, corners)
       endif
 
       ! set up MPI I/O hints for performance enhancement
-      file_info = MPI_INFO_NULL
       call MPI_Info_create(file_info, err)
 
-      ! use some ROMIO hints
-      ! call MPI_Info_set(file_info, 'romio_no_indep_rw', 'true', err)
+      ! whether doing independent or collective writes
+      if (indep_io) then
+          call MPI_Info_set(file_info, 'romio_no_indep_rw', 'false', err)
+      else
+          call MPI_Info_set(file_info, 'romio_no_indep_rw', 'true', err)
+      endif
+
+      ! disable data sieving, as FLASH-IO does large continuous writes
+      call MPI_Info_set(file_info, "romio_ds_write", "disable", err)
 
       ! disable file offset alignment for fixed-size variables
       call MPI_Info_set(file_info, "nc_var_align_size", "1", err)