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more on GPU AMG

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Ruipeng Li 2021-05-25 16:31:47 -07:00
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3
src/docs/usr-manual/ch-misc.rst
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@ -191,7 +191,8 @@ need to be set properly, which can be also set by
When configured with ``--with-cuda`` or ``--with-device-openmp``, the memory allocated on the GPUs, by default, is the GPU device memory, which is not accessible from the CPUs.
Hypre's structured solvers can work fine with device memory,
whereas only selected unstructured solvers can run with device memory. See [Running on GPUs](https://github.com/hypre-space/hypre/wiki/GPUs) for details.
whereas only selected unstructured solvers can run with device memory. See
Chapter :ref:`ch-boomeramg-gpu` for details.
In general, BoomerAMG and the SStruct
require unified (CUDA managed) memory, for which
the following option should be added

62
src/docs/usr-manual/solvers-boomeramg.rst
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@ -162,8 +162,12 @@ BoomerAMG also provides an additive V(1,1)-cycle as well as a mult-additive
V(1,1)-cycle and a simplified versioni [VaYa2014]_. The additive variants can
only be used with weighted Jacobi or l1-Jacobi smoothing.
.. _ch-boomeramg-gpu:
GPU-supported Options
------------------------------------------------------------------------------
In general, CUDA unified memory is required for running BoomerAMG solvers on GPUs,
so hypre should be configured with ``--enable-unified-memory``.
``HYPRE_Init()`` must be called and precede all the other ``HYPRE_`` functions, and
@ -177,7 +181,63 @@ The currently available GPU-supported BoomerAMG options include:
* Smoother: Jacobi, l1-Jacobi, hybrid Gauss Seidel/SRROR, two-stage Gauss-Seidel [BKRHSMTY2021]_
* Relaxation order: must be 0, i.e., lexicographic order
For details, other GPU-related functions and sample code, see [Running on GPUs](https://github.com/hypre-space/hypre/wiki/GPUs).
A sample code of setting up IJ matrix :math:`A` and solve :math:`Ax=b` using AMG-preconditioned CG
on GPUs is shown below.
.. code-block:: c
cudaSetDevice(device_id); /* GPU binding */
...
HYPRE_Init(); /* must be the first HYPRE function call */
...
/* AMG in GPU memory (default) */
HYPRE_SetMemoryLocation(HYPRE_MEMORY_DEVICE);
/* setup AMG on GPUs */
HYPRE_SetExecutionPolicy(HYPRE_EXEC_DEVICE);
/* use hypre's SpGEMM instead of cuSPARSE */
HYPRE_SetSpGemmUseCusparse(FALSE);
/* use GPU RNG */
HYPRE_SetUseGpuRand(TRUE);
if (useHypreGpuMemPool)
{
/* use hypre's GPU memory pool */
HYPRE_SetGPUMemoryPoolSize(bin_growth, min_bin, max_bin, max_bytes);
}
else if (useUmpireGpuMemPool)
{
/* or use Umpire GPU memory pool */
HYPRE_SetUmpireUMPoolName("HYPRE_UM_POOL_TEST");
HYPRE_SetUmpireDevicePoolName("HYPRE_DEVICE_POOL_TEST");
}
...
/* setup IJ matrix A */
HYPRE_IJMatrixCreate(comm, first_row, last_row, first_col, last_col, &ij_A);
HYPRE_IJMatrixSetObjectType(ij_A, HYPRE_PARCSR);
/* GPU pointers; efficient in large chunks */
HYPRE_IJMatrixAddToValues(ij_A, num_rows, num_cols, rows, cols, data);
HYPRE_IJMatrixAssemble(ij_A);
HYPRE_IJMatrixGetObject(ij_A, (void **) &parcsr_A);
...
/* setup AMG */
HYPRE_ParCSRPCGCreate(comm, &solver);
HYPRE_BoomerAMGCreate(&precon);
HYPRE_BoomerAMGSetRelaxType(precon, rlx_type); /* 7, 18, 11, 12, (3, 4, 6) */
HYPRE_BoomerAMGSetRelaxOrder(precon, FALSE); /* must be false */
HYPRE_BoomerAMGSetCoarsenType(precon, coarsen_type); /* 8 */
HYPRE_BoomerAMGSetInterpType(precon, interp_type); /* 3, 15, 6, 14, 18 */
HYPRE_BoomerAMGSetAggNumLevels(precon, agg_num_levels);
HYPRE_BoomerAMGSetAggInterpType(precon, agg_interp_type); /* 5 or 7 */
HYPRE_BoomerAMGSetKeepTranspose(precon, TRUE); /* keep transpose to avoid SpMTV */
HYPRE_BoomerAMGSetRAP2(precon, FALSE); /* RAP in two multiplications
(default: FALSE) */
HYPRE_ParCSRPCGSetPrecond(solver, HYPRE_BoomerAMGSolve, HYPRE_BoomerAMGSetup,
precon);
HYPRE_PCGSetup(solver, parcsr_A, b, x);
...
/* solve */
HYPRE_PCGSolve(solver, parcsr_A, b, x);
...
HYPRE_Finalize(); /* must be the last HYPRE function call */
Miscellaneous
------------------------------------------------------------------------------