xref: /libCEED/examples/petsc/README.md (revision 5754ecac3b7d1ff97b39b25dc78c06350f2c900d) 
1## libCEED + PETSc Examples
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3### CEED bakeoff problems with raw mesh management - bpsraw
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5This code solves the CEED bakeoff problems on a structured grid generated and referenced using only low-level communication primitives.
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7To build, run `make bpsraw`
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9To run, `./bpsraw -ceed [ceed-resource] -problem bp[1-6] -degree [degree]`
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11In addition to the common arguments, the following arguments may be set:
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13- `-local`             - Target number of locally owned DoFs per process
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15### CEED bakeoff problems with DMPlex - bps
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17This code solves the CEED bakeoff problems on a unstructured grid using DMPlex.
18This example requires a PETSc version later than 3.11.3.
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20To build, run `make bps`
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22To run, `./bps -ceed [ceed-resource] -problem bp[1-6] -degree [degree]`
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24In addition to the common arguments, the following arguments may be set:
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26- `-mesh`              - Read mesh from file
27- `-cells`             - Number of cells per dimension
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29#### Running a suite
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31Some run-time arguments can be passed lists, which allows a single `mpiexec` invocation to run many experiments.
32For example
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34    mpiexec -n 64 ./bps -problem bp1,bp2,bp3,bp4 -degree 2,3,5,7                \
35        -ceed /cpu/self/opt/serial,/cpu/self/xsmm/serial,/cpu/self/xsmm/blocked \
36        -local_nodes 600,20000 | tee bps.log
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38which will sample from the `4*4*3=48` specified combinations, each of which will run a problem-size sweep of 600, 1200, 2400, 4800, 9600, 192000 FEM nodes per MPI rank.
39The resulting log file can be read by the Python plotting scripts in `benchmarks/`.
40
41### CEED bakeoff problems with DMPlex and PCMG - multigrid
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43This code solves the CEED bakeoff problems on a unstructured grid using DMPlex with p-multigrid implemented in PCMG.
44This example requires a PETSc version later than 3.11.3.
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46To build, run `make multigrid`
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48To run, `./multigrid -ceed [ceed-resource] -problem bp[1-6] -degree [degree]`
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50In addition to the common arguments, the following arguments may be set:
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52- `-mesh`              - Read mesh from file
53- `-cells`             - Number of cells per dimension
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55### Command line arguments
56
57The following arguments can be specified for all of the above examples:
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59- `-ceed`              - CEED resource specifier
60- `-problem`           - CEED benchmark problem to solve
61- `-degree`            - Polynomial degree of tensor product basis
62- `-qextra`            - Number of extra quadrature points
63- `-test`              - Testing mode (do not print unless error is large)
64- `-benchmark`         - Benchmarking mode (prints benchmark statistics)
65
66### libCEED example to compute surface area using DMPlex - area
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68This example uses the mass matrix to compute the surface area of a cube or a discrete cubed-sphere, defined via DMPlex.
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70To build, run `make area`
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72To run, `./area -problem cube -ceed [ceed-resource] -petscspace_degree [degree]`
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74or
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76`./area -problem sphere -ceed [ceed-resource] -petscspace_degree [degree]`
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78#### Command line arguments
79
80The following arguments can be specified for the area example:
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82- `-ceed`              - CEED resource specifier
83- `-problem`           - Problem to solve, either 'cube' or 'sphere'
84- `-petscspace_degree` - Polynomial degree of tensor product basis
85- `-qextra`            - Number of extra quadrature points
86- `-test`              - Testing mode (do not print unless error is large)
87- `-mesh`              - Read mesh from file
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89