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36 // FIXME: remove the "__" prefix in front of the group def when we move the
37 // nonbonded code into separate dir.
39 /*! \libinternal \defgroup __module_nbnxm Short-range non-bonded interaction module
40 * \ingroup group_mdrun
42 * \brief Computes forces and energies for short-range pair-interactions
43 * based on the Verlet algorithm. The algorithm uses pair-lists generated
44 * at fixed intervals as well as various flavors of pair interaction kernels
45 * implemented for a wide range of CPU and GPU architectures.
47 * The module includes support for flavors of Coulomb and Lennard-Jones interaction
48 * treatment implemented for a large range of SIMD instruction sets for CPU
49 * architectures as well as in CUDA and OpenCL for GPU architectures.
50 * Additionally there is a reference CPU non-SIMD and a reference CPU
51 * for GPU pair-list setup interaction kernel.
53 * The implementation of the kernels is based on the cluster non-bonded algorithm
54 * which in the code is referred to as the NxM algorithms ("nbnxm_" prefix);
55 * for details of the algorithm see DOI:10.1016/j.cpc.2013.06.003.
57 * Algorithmically, the non-bonded computation has two different modes:
58 * A "classical" mode: generate a list every nstlist steps containing at least
59 * all atom pairs up to a distance of rlistOuter and compute pair interactions
60 * for all pairs that are within the interaction cut-off.
61 * A "dynamic pruning" mode: generate an "outer-list" up to cut-off rlistOuter
62 * every nstlist steps and prune the outer-list using a cut-off of rlistInner
63 * every nstlistPrune steps to obtain a, smaller, "inner-list". This
64 * results in fewer interaction computations and allows for a larger nstlist.
65 * On a GPU, this dynamic pruning is performed in a rolling fashion, pruning
66 * only a sub-part of the list each (second) step. This way it can often
67 * overlap with integration and constraints on the CPU.
68 * Currently a simple heuristic determines which mode will be used.
70 * TODO: add a summary list and brief descriptions of the different submodules:
71 * search, CPU kernels, GPU glue code + kernels.
73 * \author Berk Hess <hess@kth.se>
74 * \author Szilárd Páll <pall.szilard@gmail.com>
75 * \author Mark Abraham <mark.j.abraham@gmail.com>
76 * \author Anca Hamuraru <anca@streamcomputing.eu>
77 * \author Teemu Virolainen <teemu@streamcomputing.eu>
78 * \author Dimitrios Karkoulis <dimitris.karkoulis@gmail.com>
80 * TODO: add more authors!
83 /*! \libinternal \file
85 * \brief This file contains the public interface of the nbnxm module
86 * that implements the NxM atom cluster non-bonded algorithm to efficiently
87 * compute pair forces.
90 * \author Berk Hess <hess@kth.se>
91 * \author Szilárd Páll <pall.szilard@gmail.com>
94 * \ingroup __module_nbnxm
98 #ifndef GMX_NBNXM_NBNXM_H
99 #define GMX_NBNXM_NBNXM_H
103 #include "gromacs/math/vectypes.h"
104 #include "gromacs/nbnxm/pairlist.h"
105 #include "gromacs/utility/arrayref.h"
106 #include "gromacs/utility/enumerationhelpers.h"
107 #include "gromacs/utility/real.h"
109 #include "locality.h"
111 // TODO: Remove this include and the two nbnxm includes above
112 #include "nbnxm_gpu.h"
114 struct gmx_device_info_t;
115 struct gmx_domdec_zones_t;
116 struct gmx_enerdata_t;
117 struct gmx_hw_info_t;
119 struct interaction_const_t;
120 struct nbnxn_pairlist_set_t;
122 struct nonbonded_verlet_t;
134 class UpdateGroupsCog;
137 /*! \brief Resources that can be used to execute non-bonded kernels on */
138 enum class NonbondedResource : int
148 /*! \brief Nonbonded NxN kernel types: plain C, CPU SIMD, GPU, GPU emulation */
149 enum class KernelType : int
160 /*! \brief Ewald exclusion types */
161 enum class EwaldExclusionType : int
169 /* \brief The non-bonded setup, also affects the pairlist construction kernel */
172 //! The non-bonded type, also affects the pairlist construction kernel
173 KernelType kernelType = KernelType::NotSet;
174 //! Ewald exclusion computation handling type, currently only used for CPU
175 EwaldExclusionType ewaldExclusionType = EwaldExclusionType::NotSet;
178 /*! \brief Return a string identifying the kernel type.
180 * \param [in] kernelType nonbonded kernel type, takes values from the nbnxn_kernel_type enum
181 * \returns a string identifying the kernel corresponding to the type passed as argument
183 const char *lookup_kernel_name(Nbnxm::KernelType kernelType);
187 /*! \brief Flag to tell the nonbonded kernels whether to clear the force output buffers */
189 enbvClearFNo, enbvClearFYes
192 /*! \brief Generates a pair-list for the given locality.
194 * With perturbed particles, also a group scheme style nbl_fep list is made.
196 void nbnxn_make_pairlist(nonbonded_verlet_t *nbv,
197 Nbnxm::InteractionLocality iLocality,
198 nbnxn_pairlist_set_t *pairlistSet,
199 const t_blocka *excl,
203 /*! \brief Prune all pair-lists with given locality (currently CPU only)
205 * For all pair-lists with given locality, takes the outer list and prunes out
206 * pairs beyond the pairlist inner radius and writes the result to a list that is
207 * to be consumed by the non-bonded kernel.
209 void NbnxnDispatchPruneKernel(nbnxn_pairlist_set_t *pairlistSet,
210 Nbnxm::KernelType kernelType,
211 const nbnxn_atomdata_t *nbat,
212 const rvec *shift_vec);
215 * \brief Top-level non-bonded data structure for the Verlet-type cut-off scheme. */
216 struct nonbonded_verlet_t
219 //! Returns whether a GPU is use for the non-bonded calculations
222 return kernelSetup_.kernelType == Nbnxm::KernelType::Gpu8x8x8;
225 //! Returns whether a GPU is emulated for the non-bonded calculations
226 bool emulateGpu() const
228 return kernelSetup_.kernelType == Nbnxm::KernelType::Cpu8x8x8_PlainC;
231 //! Return whether the pairlist is of simple, CPU type
232 bool pairlistIsSimple() const
234 return !useGpu() && !emulateGpu();
237 //! Initialize the pair list sets, TODO this should be private
238 void initPairlistSets(bool haveMultipleDomains);
240 //! Returns a reference to the pairlist set for the requested locality
241 const nbnxn_pairlist_set_t &pairlistSet(Nbnxm::InteractionLocality iLocality) const
243 GMX_ASSERT(static_cast<size_t>(iLocality) < pairlistSets_.size(),
244 "The requested locality should be in the list");
245 return pairlistSets_[static_cast<int>(iLocality)];
248 //! Constructs the pairlist for the given locality
249 void constructPairlist(Nbnxm::InteractionLocality iLocality,
250 const t_blocka *excl,
254 nbnxn_make_pairlist(this, iLocality, &pairlistSets_[static_cast<int>(iLocality)], excl, step, nrnb);
257 //! Dispatches the dynamic pruning kernel for the given locality
258 void dispatchPruneKernel(Nbnxm::InteractionLocality iLocality,
259 const rvec *shift_vec)
261 GMX_ASSERT(static_cast<size_t>(iLocality) < pairlistSets_.size(),
262 "The requested locality should be in the list");
263 NbnxnDispatchPruneKernel(&pairlistSets_[static_cast<int>(iLocality)],
264 kernelSetup_.kernelType, nbat, shift_vec);
267 //! Dispatches the non-bonded free-energy kernel, always runs on the CPU
268 void dispatchFreeEnergyKernel(Nbnxm::InteractionLocality iLocality,
272 const t_mdatoms &mdatoms,
275 gmx_enerdata_t *enerd,
279 //! Return the kernel setup
280 const Nbnxm::KernelSetup &kernelSetup() const
285 //! Sets the kernel setup, TODO: make private
286 void setKernelSetup(const Nbnxm::KernelSetup &kernelSetup)
288 kernelSetup_ = kernelSetup;
291 //! Parameters for the search and list pruning setup
292 std::unique_ptr<NbnxnListParameters> listParams;
293 //! Working data for constructing the pairlists
294 std::unique_ptr<nbnxn_search> nbs;
296 //! Local and, optionally, non-local pairlist sets
297 std::vector<nbnxn_pairlist_set_t> pairlistSets_;
300 nbnxn_atomdata_t *nbat;
303 //! The non-bonded setup, also affects the pairlist construction kernel
304 Nbnxm::KernelSetup kernelSetup_;
307 gmx_nbnxn_gpu_t *gpu_nbv; /**< pointer to GPU nb verlet data */
308 int min_ci_balanced; /**< pair list balancing parameter used for the 8x8x8 GPU kernels */
314 /*! \brief Initializes the nbnxn module */
315 void init_nb_verlet(const gmx::MDLogger &mdlog,
316 nonbonded_verlet_t **nb_verlet,
317 gmx_bool bFEP_NonBonded,
318 const t_inputrec *ir,
319 const t_forcerec *fr,
321 const gmx_hw_info_t &hardwareInfo,
322 const gmx_device_info_t *deviceInfo,
323 const gmx_mtop_t *mtop,
328 /*! \brief Put the atoms on the pair search grid.
330 * Only atoms atomStart to atomEnd in x are put on the grid.
331 * The atom_density is used to determine the grid size.
332 * When atomDensity<=0, the density is determined from atomEnd-atomStart and the corners.
333 * With domain decomposition part of the n particles might have migrated,
334 * but have not been removed yet. This count is given by nmoved.
335 * When move[i] < 0 particle i has migrated and will not be put on the grid.
336 * Without domain decomposition move will be NULL.
338 void nbnxn_put_on_grid(nonbonded_verlet_t *nb_verlet,
341 const rvec lowerCorner,
342 const rvec upperCorner,
343 const gmx::UpdateGroupsCog *updateGroupsCog,
348 gmx::ArrayRef<const gmx::RVec> x,
352 /*! \brief As nbnxn_put_on_grid, but for the non-local atoms
354 * with domain decomposition. Should be called after calling
355 * nbnxn_search_put_on_grid for the local atoms / home zone.
357 void nbnxn_put_on_grid_nonlocal(nonbonded_verlet_t *nb_verlet,
358 const struct gmx_domdec_zones_t *zones,
360 gmx::ArrayRef<const gmx::RVec> x);
362 /*! \brief Returns the number of x and y cells in the local grid */
363 void nbnxn_get_ncells(const nbnxn_search *nbs, int *ncx, int *ncy);
365 /*! \brief Returns the order indices of the atoms on the pairlist search grid */
366 gmx::ArrayRef<const int> nbnxn_get_atomorder(const nbnxn_search* nbs);
368 /*! \brief Renumbers the atom indices on the grid to consecutive order */
369 void nbnxn_set_atomorder(nbnxn_search *nbs);
371 /*! \brief Returns the index position of the atoms on the pairlist search grid */
372 gmx::ArrayRef<const int> nbnxn_get_gridindices(const nbnxn_search* nbs);
374 /*! \brief Returns the number of steps performed with the current pair list */
375 int nbnxnNumStepsWithPairlist(const nonbonded_verlet_t &nbv,
376 Nbnxm::InteractionLocality ilocality,
379 /*! \brief Returns whether step is a dynamic list pruning step */
380 bool nbnxnIsDynamicPairlistPruningStep(const nonbonded_verlet_t &nbv,
381 Nbnxm::InteractionLocality ilocality,
384 /*! \brief Executes the non-bonded kernel of the GPU or launches it on the GPU */
385 void NbnxnDispatchKernel(nonbonded_verlet_t *nbv,
386 Nbnxm::InteractionLocality iLocality,
387 const interaction_const_t &ic,
391 gmx_enerdata_t *enerd,
394 #endif // GMX_NBNXN_NBNXN_H