Difference between revisions of "Main Page/PIO"
From Nekcem
Jump to navigationJump to search| Line 11: | Line 11: | ||
These three approaches produce one file per processor and we will refer them as ''old libraries''. <br> | These three approaches produce one file per processor and we will refer them as ''old libraries''. <br> | ||
| − | : '''param(81) = 1''': use nek5000 old_output format | + | : '''param(81) = 1''': use nek5000 old_output format (ASCII, fld format, xxx-.fld). <br> |
| − | : '''param(81) = 2''': use Fortran I/O library (ASCII, VTK format). <br> | + | : '''param(81) = 2''': use Fortran I/O library (ASCII, VTK format, ascii-xxx-.vtk). <br> |
: '''param(81) = 3''': use C-POSIX I/O libraries (binary, VTK format). <br> | : '''param(81) = 3''': use C-POSIX I/O libraries (binary, VTK format). <br> | ||
---- | ---- | ||
| − | Several advanced parallel I/O approaches were developed. The details are described[http://www.mcs.anl.gov/~mmin/ICS2011.pdf]. | + | Several advanced parallel I/O approaches were developed. The details are described[http://www.mcs.anl.gov/~mmin/ICS2011.pdf]. |
| − | '''param(81) = 4''': collective for N processors IO to 1 file (mpi-binary-N1.vtk) <br> | + | : '''param(81) = 4''': collective for N processors IO to 1 file (mpi-binary-N1-xxx.vtk) <br> |
| − | '''param(81) = 5''' | + | : '''param(81) = 5''': collective IO for N processors to multiple M-files (mpi-binary-NM-xxx.vtk. <br> |
| − | '''param(103) = 6''' | + | : '''param(103) = 6''': reduced-blocking IO for N processors to 1 file with M writers (mpi-binary-NM1-xxx.vtk). ,br> |
| + | |||
| + | : '''param(103) = 6''': reduced-blocking IO for N processors to 1 file with M writers (mpi-ascii-NM1-xxx.vtk). ,br> | ||
| + | |||
| + | : '''param(103) = 8''': reduced-blocking IO for N processors to multiple M-files with M writers (mpi-NMM-xxx.vtk). <br> | ||
| − | |||
| − | |||
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 groups, param(83) = max number of fields we are going to write. | param(82) = number of groups, param(83) = max number of fields we are going to write. | ||
Revision as of 10:39, 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:
For traditional approaches based on one file per processor, users can use #1,2,3
in .rea file for a specific example, by parameter 81.
These three approaches produce one file per processor and we will refer them as old libraries.
- param(81) = 1: use nek5000 old_output format (ASCII, fld format, xxx-.fld).
- 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).
Several advanced parallel I/O approaches were developed. The details are described[1].
- param(81) = 4: collective for N processors IO to 1 file (mpi-binary-N1-xxx.vtk)
- param(81) = 5: collective IO for N processors to multiple M-files (mpi-binary-NM-xxx.vtk.
- param(103) = 6: reduced-blocking IO for N processors to 1 file with M writers (mpi-binary-NM1-xxx.vtk). ,br>
- param(103) = 6: reduced-blocking IO for N processors to 1 file with M writers (mpi-ascii-NM1-xxx.vtk). ,br>
- param(103) = 8: reduced-blocking IO for N processors to multiple M-files with M writers (mpi-NMM-xxx.vtk).
Note that param(82) and param(83) need to be set correctly in *.rea file.
param(82) = number of groups, param(83) = max number of fields we are going to write.
