Difference between revisions of "Main Page/faq"
From Nekcem
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=== NekCEM notes=== | === NekCEM notes=== | ||
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* scaling | * scaling | ||
** 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. | ||
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* only CELL and point data need to be re-computed | * only CELL and point data need to be re-computed | ||
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| + | * compile and run NekCEM | ||
| + | ** in a specific case, ../../bin/cleanall, ../../bin/makenek, ../../bin/nek "case_name" #proc | ||
| + | ** e.g., in cylwave, ../../bin/nek cylwave 4 | ||
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== To-do List == | == To-do List == | ||
*More tests on BG/P for config with ng = M and 1< nf < M | *More tests on BG/P for config with ng = M and 1< nf < M | ||
Revision as of 19:48, 24 February 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
- 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; size = #grid point * 3 * float
- cell type: 2d → 4 * #cell * int + 1* #cell * int (3d → 9)
- #field = nfields * 3 * #grid point; size = #field * float;
- .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
- compile and run NekCEM
- in a specific case, ../../bin/cleanall, ../../bin/makenek, ../../bin/nek "case_name" #proc
- e.g., in cylwave, ../../bin/nek cylwave 4
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
Miscellaneous 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 ..
