Difference between revisions of "Main Page/faq"
From Nekcem
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** strong scaling: defined as how the solution time varies with the number of processors for a fixed total problem size. | ** strong scaling: defined as how the solution time varies with the number of processors for a fixed total problem size. | ||
** weak scaling: defined as how the solution time varies with the number of processors for a fixed problem size per processor. | ** weak scaling: defined as how the solution time varies with the number of processors for a fixed problem size per processor. | ||
| + | * pre-compute file size | ||
| + | ** grid point (nx * ny * nz * nelt) | ||
| + | ** cell type | ||
| + | ** field (nfields * 3 *nx *ny * nx * nelt) | ||
| + | |||
* .box → num elements in x,y,z | * .box → num elements in x,y,z | ||
* .rea → input data | * .rea → input data | ||
Revision as of 22:33, 31 January 2011
This is the resource listing page for NekCEM.
Resource Links
Implementation
I/O code
- I/O functions were initiated from cem_out function of cem_dg.F (and cem_dg2.F).
- Implementation of parallel I/O routine were defined in vtkbin.c and rbIO_nekcem.c
- vtkcommon.c and vtkcommon.h serve as a place to hold common functions as well as global variables.
- cem_out_fields3 (in cem_dg.F)
- openfile3(dumpno, nid) !vtkbin.c
- vtk_dump_header3
- writeheader3() !vtkbin.c
- writenodes3() !vtkbin.c
- write2dcells3 !vtkbin.c
or write3dcells3 !vtkbin.c
- vtk_dump_field3
- writefield3 !vtkbin.c
- close_file3 !vtkbin.c
- Binary file → ASCII file: transfer double/float/int/read to chars then write out
- float (4 bytes) → %18.8E
- int (4 bytes) → %10d
- long long (8 bytes) → %18lld
- elemType → %4d
NekCEM notes for myself
- scaling
- strong scaling: defined as how the solution time varies with the number of processors for a fixed total problem size.
- weak scaling: defined as how the solution time varies with the number of processors for a fixed problem size per processor.
- pre-compute file size
- grid point (nx * ny * nz * nelt)
- cell type
- field (nfields * 3 *nx *ny * nx * nelt)
- .box → num elements in x,y,z
- .rea → input data
- SIZEu → SIZE parameters:
- lxi ?
- lp = #proc
- lelx = 20 each dimension
- lelv = alloc max # of element per proc
- .usr → subuser.F
- cem() in cem_dg.F is the main solver and application entry point
- only CELL and point data need to be re-computed
To-do List
- More tests on BG/P for config with ng = M and 1< nf < M
- Tests on Kraken and Jaguar
- Pthread + MPI for I/O
- OpenMP/Pthread + MPI for NekCEM computation
- Parallel I/O for reading .rea file
Some notes
- Fortran generated binary file may not be correctly read in C.
- -lstdc++ for link
- libF77 and libI77
- common.h and common_c.h
- write() in Fortran: 6 refer to screen, * is to screen as well ..
