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36 /*! \libinternal \file
37 * \brief Declare interface for GPU execution for NBNXN module
39 * \author Szilard Pall <pall.szilard@gmail.com>
40 * \author Mark Abraham <mark.j.abraham@gmail.com>
41 * \ingroup module_nbnxm
44 #ifndef GMX_NBNXM_NBNXM_GPU_H
45 #define GMX_NBNXM_NBNXM_GPU_H
47 #include "gromacs/gpu_utils/gpu_macros.h"
48 #include "gromacs/math/vectypes.h"
49 #include "gromacs/mdtypes/locality.h"
50 #include "gromacs/utility/basedefinitions.h"
51 #include "gromacs/utility/real.h"
54 #include "gpu_types.h"
56 struct interaction_const_t;
57 struct nbnxn_atomdata_t;
59 enum class GpuTaskCompletion;
73 * Launch asynchronously the xq buffer host to device copy.
75 * The nonlocal copy is skipped if there is no dependent work to do,
76 * neither non-local nonbonded interactions nor bonded GPU work.
78 * \param [in] nb GPU nonbonded data.
79 * \param [in] nbdata Host-side atom data structure.
80 * \param [in] aloc Atom locality flag.
83 void gpu_copy_xq_to_gpu(gmx_nbnxn_gpu_t gmx_unused* nb,
84 const struct nbnxn_atomdata_t gmx_unused* nbdata,
85 gmx::AtomLocality gmx_unused aloc) GPU_FUNC_TERM;
88 * Launch asynchronously the nonbonded force calculations.
90 * Also launches the initial pruning of a fresh list after search.
92 * The local and non-local interaction calculations are launched in two
93 * separate streams. If there is no work (i.e. empty pair list), the
94 * force kernel launch is omitted.
98 void gpu_launch_kernel(gmx_nbnxn_gpu_t gmx_unused* nb,
99 const gmx::StepWorkload gmx_unused& stepWork,
100 gmx::InteractionLocality gmx_unused iloc) GPU_FUNC_TERM;
103 * Launch asynchronously the nonbonded prune-only kernel.
105 * The local and non-local list pruning are launched in their separate streams.
107 * Notes for future scheduling tuning:
108 * Currently we schedule the dynamic pruning between two MD steps *after* both local and
109 * nonlocal force D2H transfers completed. We could launch already after the cpyback
110 * is launched, but we want to avoid prune kernels (especially in the non-local
111 * high prio-stream) competing with nonbonded work.
113 * However, this is not ideal as this schedule does not expose the available
114 * concurrency. The dynamic pruning kernel:
115 * - should be allowed to overlap with any task other than force compute, including
116 * transfers (F D2H and the next step's x H2D as well as force clearing).
117 * - we'd prefer to avoid competition with non-bonded force kernels belonging
118 * to the same rank and ideally other ranks too.
120 * In the most general case, the former would require scheduling pruning in a separate
121 * stream and adding additional event sync points to ensure that force kernels read
122 * consistent pair list data. This would lead to some overhead (due to extra
123 * cudaStreamWaitEvent calls, 3-5 us/call) which we might be able to live with.
124 * The gains from additional overlap might not be significant as long as
125 * update+constraints anyway takes longer than pruning, but there will still
126 * be use-cases where more overlap may help (e.g. multiple ranks per GPU,
127 * no/hbonds only constraints).
128 * The above second point is harder to address given that multiple ranks will often
129 * share a GPU. Ranks that complete their nonbondeds sooner can schedule pruning earlier
130 * and without a third priority level it is difficult to avoid some interference of
131 * prune kernels with force tasks (in particular preemption of low-prio local force task).
133 * \param [inout] nb GPU nonbonded data.
134 * \param [in] iloc Interaction locality flag.
135 * \param [in] numParts Number of parts the pair list is split into in the rolling kernel.
138 void gpu_launch_kernel_pruneonly(gmx_nbnxn_gpu_t gmx_unused* nb,
139 gmx::InteractionLocality gmx_unused iloc,
140 int gmx_unused numParts) GPU_FUNC_TERM;
143 * Launch asynchronously the download of short-range forces from the GPU
144 * (and energies/shift forces if required).
147 void gpu_launch_cpyback(gmx_nbnxn_gpu_t gmx_unused* nb,
148 nbnxn_atomdata_t gmx_unused* nbatom,
149 const gmx::StepWorkload gmx_unused& stepWork,
150 gmx::AtomLocality gmx_unused aloc) GPU_FUNC_TERM;
152 /*! \brief Attempts to complete nonbonded GPU task.
154 * This function attempts to complete the nonbonded task (both GPU and CPU auxiliary work).
155 * Success, i.e. that the tasks completed and results are ready to be consumed, is signaled
156 * by the return value (always true if blocking wait mode requested).
158 * The \p completionKind parameter controls whether the behavior is non-blocking
159 * (achieved by passing GpuTaskCompletion::Check) or blocking wait until the results
160 * are ready (when GpuTaskCompletion::Wait is passed).
161 * As the "Check" mode the function will return immediately if the GPU stream
162 * still contain tasks that have not completed, it allows more flexible overlapping
163 * of work on the CPU with GPU execution.
165 * Note that it is only safe to use the results, and to continue to the next MD
166 * step when this function has returned true which indicates successful completion of
167 * - All nonbonded GPU tasks: both compute and device transfer(s)
168 * - auxiliary tasks: updating the internal module state (timing accumulation, list pruning states) and
169 * - internal staging reduction of (\p fshift, \p e_el, \p e_lj).
171 * In GpuTaskCompletion::Check mode this function does the timing and keeps correct count
172 * for the nonbonded task (incrementing only once per taks), in the GpuTaskCompletion::Wait mode
173 * timing is expected to be done in the caller.
175 * TODO: improve the handling of outputs e.g. by ensuring that this function explcitly returns the
176 * force buffer (instead of that being passed only to nbnxn_gpu_launch_cpyback()) and by returning
177 * the energy and Fshift contributions for some external/centralized reduction.
179 * \param[in] nb The nonbonded data GPU structure
180 * \param[in] stepWork Step schedule flags
181 * \param[in] aloc Atom locality identifier
182 * \param[out] e_lj Pointer to the LJ energy output to accumulate into
183 * \param[out] e_el Pointer to the electrostatics energy output to accumulate into
184 * \param[out] shiftForces Shift forces buffer to accumulate into
185 * \param[in] completionKind Indicates whether nnbonded task completion should only be checked rather than waited for
186 * \param[out] wcycle Pointer to wallcycle data structure
187 * \returns True if the nonbonded tasks associated with \p aloc locality have completed
190 bool gpu_try_finish_task(gmx_nbnxn_gpu_t gmx_unused* nb,
191 const gmx::StepWorkload gmx_unused& stepWork,
192 gmx::AtomLocality gmx_unused aloc,
193 real gmx_unused* e_lj,
194 real gmx_unused* e_el,
195 gmx::ArrayRef<gmx::RVec> gmx_unused shiftForces,
196 GpuTaskCompletion gmx_unused completionKind,
197 gmx_wallcycle gmx_unused* wcycle) GPU_FUNC_TERM_WITH_RETURN(false);
199 /*! \brief Completes the nonbonded GPU task blocking until GPU tasks and data
200 * transfers to finish.
202 * Also does timing accounting and reduction of the internal staging buffers.
203 * As this is called at the end of the step, it also resets the pair list and
206 * \param[in] nb The nonbonded data GPU structure
207 * \param[in] stepWork Step schedule flags
208 * \param[in] aloc Atom locality identifier
209 * \param[out] e_lj Pointer to the LJ energy output to accumulate into
210 * \param[out] e_el Pointer to the electrostatics energy output to accumulate into
211 * \param[out] shiftForces Shift forces buffer to accumulate into
212 * \param[out] wcycle Pointer to wallcycle data structure */
214 float gpu_wait_finish_task(gmx_nbnxn_gpu_t gmx_unused* nb,
215 const gmx::StepWorkload gmx_unused& stepWork,
216 gmx::AtomLocality gmx_unused aloc,
217 real gmx_unused* e_lj,
218 real gmx_unused* e_el,
219 gmx::ArrayRef<gmx::RVec> gmx_unused shiftForces,
220 gmx_wallcycle gmx_unused* wcycle) GPU_FUNC_TERM_WITH_RETURN(0.0);
222 /*! \brief Selects the Ewald kernel type, analytical or tabulated, single or twin cut-off. */
224 int nbnxn_gpu_pick_ewald_kernel_type(const interaction_const_t gmx_unused& ic)
225 GPU_FUNC_TERM_WITH_RETURN(-1);
227 /*! \brief Initialization for X buffer operations on GPU.
228 * Called on the NS step and performs (re-)allocations and memory copies. !*/
230 void nbnxn_gpu_init_x_to_nbat_x(const Nbnxm::GridSet gmx_unused& gridSet,
231 gmx_nbnxn_gpu_t gmx_unused* gpu_nbv) CUDA_FUNC_TERM;
233 /*! \brief X buffer operations on GPU: performs conversion from rvec to nb format.
235 * \param[in] grid Grid to be converted.
236 * \param[in] setFillerCoords If the filler coordinates are used.
237 * \param[in,out] gpu_nbv The nonbonded data GPU structure.
238 * \param[in] d_x Device-side coordinates in plain rvec format.
239 * \param[in] xReadyOnDevice Event synchronizer indicating that the coordinates are ready in
240 * the device memory. \param[in] locality Copy coordinates for local or non-local atoms.
241 * \param[in] gridId Index of the grid being converted.
242 * \param[in] numColumnsMax Maximum number of columns in the grid.
245 void nbnxn_gpu_x_to_nbat_x(const Nbnxm::Grid gmx_unused& grid,
246 bool gmx_unused setFillerCoords,
247 gmx_nbnxn_gpu_t gmx_unused* gpu_nbv,
248 DeviceBuffer<float> gmx_unused d_x,
249 GpuEventSynchronizer gmx_unused* xReadyOnDevice,
250 gmx::AtomLocality gmx_unused locality,
251 int gmx_unused gridId,
252 int gmx_unused numColumnsMax) CUDA_FUNC_TERM;
254 /*! \brief Sync the nonlocal stream with dependent tasks in the local queue.
255 * \param[in] nb The nonbonded data GPU structure
256 * \param[in] interactionLocality Local or NonLocal sync point
259 void nbnxnInsertNonlocalGpuDependency(const gmx_nbnxn_gpu_t gmx_unused* nb,
260 gmx::InteractionLocality gmx_unused interactionLocality) CUDA_FUNC_TERM;
262 /*! \brief Set up internal flags that indicate what type of short-range work there is.
264 * As nonbondeds and bondeds share input/output buffers and GPU queues,
265 * both are considered when checking for work in the current domain.
267 * This function is expected to be called every time the work-distribution
268 * can change (i.e. at search/domain decomposition steps).
270 * \param[inout] nb Pointer to the nonbonded GPU data structure
271 * \param[in] gpuBonded Pointer to the GPU bonded data structure
272 * \param[in] iLocality Interaction locality identifier
275 void setupGpuShortRangeWork(gmx_nbnxn_gpu_t gmx_unused* nb,
276 const gmx::GpuBonded gmx_unused* gpuBonded,
277 gmx::InteractionLocality gmx_unused iLocality) GPU_FUNC_TERM;
279 /*! \brief Returns true if there is GPU short-range work for the given atom locality.
281 * Note that as, unlike nonbonded tasks, bonded tasks are not split into local/nonlocal,
282 * and therefore if there are GPU offloaded bonded interactions, this function will return
283 * true for both local and nonlocal atom range.
285 * \param[inout] nb Pointer to the nonbonded GPU data structure
286 * \param[in] aLocality Atom locality identifier
289 bool haveGpuShortRangeWork(const gmx_nbnxn_gpu_t gmx_unused* nb, gmx::AtomLocality gmx_unused aLocality)
290 GPU_FUNC_TERM_WITH_RETURN(false);
292 /*! \brief Initialization for F buffer operations on GPU */
294 void nbnxn_gpu_init_add_nbat_f_to_f(const int gmx_unused* cell,
295 gmx_nbnxn_gpu_t gmx_unused* gpu_nbv,
296 int gmx_unused natoms_total,
297 GpuEventSynchronizer gmx_unused* localReductionDone) CUDA_FUNC_TERM;
299 /*! \brief Force buffer operations on GPU.
301 * Transforms non-bonded forces into plain rvec format and add all the force components to the total
304 * \param[in] atomLocality If the reduction should be performed on local or non-local atoms.
305 * \param[in] totalForcesDevice Device buffer to accumulate resulting force.
306 * \param[in] gpu_nbv The NBNXM GPU data structure.
307 * \param[in] pmeForcesDevice Device buffer with PME forces.
308 * \param[in] dependencyList List of synchronizers that represent the dependencies the reduction task needs to sync on.
309 * \param[in] atomStart Index of the first atom to reduce forces for.
310 * \param[in] numAtoms Number of atoms to reduce forces for.
311 * \param[in] useGpuFPmeReduction Whether PME forces should be added.
312 * \param[in] accumulateForce Whether there are usefull data already in the total force buffer.
316 void nbnxn_gpu_add_nbat_f_to_f(gmx::AtomLocality gmx_unused atomLocality,
317 DeviceBuffer<float> gmx_unused totalForcesDevice,
318 gmx_nbnxn_gpu_t gmx_unused* gpu_nbv,
319 void gmx_unused* pmeForcesDevice,
320 gmx::ArrayRef<GpuEventSynchronizer* const> gmx_unused dependencyList,
321 int gmx_unused atomStart,
322 int gmx_unused numAtoms,
323 bool gmx_unused useGpuFPmeReduction,
324 bool gmx_unused accumulateForce) CUDA_FUNC_TERM;
326 /*! \brief sync CPU thread on coordinate copy to device
327 * \param[in] nb The nonbonded data GPU structure
330 void nbnxn_wait_x_on_device(gmx_nbnxn_gpu_t gmx_unused* nb) CUDA_FUNC_TERM;