Difference between revisions of "Main Page/PIO"
| Line 9: | Line 9: | ||
Users can use #1,2,3,4,5,6,7,8 in .rea file for a specific example, by parameter 81. <br> | Users can use #1,2,3,4,5,6,7,8 in .rea file for a specific example, by parameter 81. <br> | ||
| − | Several '''advanced parallel I/O''' | + | Several '''advanced parallel I/O''' algorithms based on MPI-IO library were developed. <br> |
| − | + | The approaches use param(81)=4,5,6,7,8. The analysis on the performance for those | |
| − | '' | + | approaches are detailed in ''Parallel I/O performance for application-level checkpointing |
| − | + | on the Blue Gene/P '' [http://www.mcs.anl.gov/~mmin/ICS2011.pdf] by Jing Fu et. al. | |
proc=processors | proc=processors | ||
| Line 19: | Line 19: | ||
'''param(81) = 6''': reduced-blocking IO for N proc to 1 file with M writers ---> mpi-binary-NM1-xxx.vtk | '''param(81) = 6''': reduced-blocking IO for N proc to 1 file with M writers ---> mpi-binary-NM1-xxx.vtk | ||
'''param(81) = 7''': reduced-blocking IO for N proc to 1 file with M writers ---> mpi-ascii-NM1-xxx.vtk | '''param(81) = 7''': reduced-blocking IO for N proc to 1 file with M writers ---> mpi-ascii-NM1-xxx.vtk | ||
| − | '''param(81) = 8''': reduced-blocking IO for N proc to multiple M-files with M writers ---> mpi-binary-NMM-xxx.vtk | + | '''param(81) = 8''': reduced-blocking IO for N proc to multiple M-files with M writers ---> mpi-binary-NMM-xxx.vtk |
| − | |||
| − | |||
'''Note''' that param(82) and param(83) need to be set correctly in *.rea file. | '''Note''' that param(82) and param(83) need to be set correctly in *.rea file. | ||
| − | |||
'''param(82)''' = number of output files | '''param(82)''' = number of output files | ||
Revision as of 21:36, 12 June 2011
This is the document page for parallel I/O library developed for NekCEM.
Background
- File Format
- Binary (used for production, compact size), or ASCII (used for debugging, human-readable)
Usage Introduction
Users can use #1,2,3,4,5,6,7,8 in .rea file for a specific example, by parameter 81.
Several advanced parallel I/O algorithms based on MPI-IO library were developed.
The approaches use param(81)=4,5,6,7,8. The analysis on the performance for those
approaches are detailed in Parallel I/O performance for application-level checkpointing
on the Blue Gene/P [1] by Jing Fu et. al.
proc=processors param(81) = 4: collective IO for N proc to 1 file ---> mpi-binary-N1-xxx.vtk param(81) = 5: collective IO for N proc to multiple M-files ---> mpi-binary-NM-xxx.vtk param(81) = 6: reduced-blocking IO for N proc to 1 file with M writers ---> mpi-binary-NM1-xxx.vtk param(81) = 7: reduced-blocking IO for N proc to 1 file with M writers ---> mpi-ascii-NM1-xxx.vtk param(81) = 8: reduced-blocking IO for N proc to multiple M-files with M writers ---> mpi-binary-NMM-xxx.vtk
Note that param(82) and param(83) need to be set correctly in *.rea file.
param(82) = number of output files param(83) = max number of fields to be written
For traditional I/O approaches based on one file per processor, using old libraries, one can use
param(81) = 2: use Fortran I/O library (ASCII, VTK format) ---> ascii-xxx.vtk param(81) = 3: use C-POSIX I/O libraries (binary, VTK format) ---> binary-xxx.vtk
param(81) = 1: use nek5000's old output format (ASCII) -> xxx.fld
Visualization
The output files with param(81)=2,3,4,5,6,7,8 can be visualized with ParaView and VisIt.
The output with param(81)=1 can be visualized with nek5000 visualization tool, postx
