src/gromacs/ewald/pme-gpu.cpp

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  35
  36 /*! \internal \file
  37  * \brief Implements high-level PME GPU functions which do not require GPU framework-specific code.
  38  *
  39  * \author Aleksei Iupinov <a.yupinov@gmail.com>
  40  * \ingroup module_ewald
  41  */
  42
  43 #include "gmxpre.h"
  44
  45 #include "config.h"
  46
  47 #include <list>
  48
  49 #include "gromacs/ewald/ewald-utils.h"
  50 #include "gromacs/ewald/pme.h"
  51 #include "gromacs/fft/parallel_3dfft.h"
  52 #include "gromacs/math/invertmatrix.h"
  53 #include "gromacs/mdlib/gmx_omp_nthreads.h"
  54 #include "gromacs/mdtypes/enerdata.h"
  55 #include "gromacs/mdtypes/forceoutput.h"
  56 #include "gromacs/mdtypes/inputrec.h"
  57 #include "gromacs/utility/exceptions.h"
  58 #include "gromacs/utility/fatalerror.h"
  59 #include "gromacs/utility/gmxassert.h"
  60 #include "gromacs/utility/stringutil.h"
  61
  62 #include "pme-gpu-internal.h"
  63 #include "pme-grid.h"
  64 #include "pme-internal.h"
  65 #include "pme-solve.h"
  66
  67 void pme_gpu_reset_timings(const gmx_pme_t *pme)
  68 {
  69     if (pme_gpu_active(pme))
  70     {
  71         pme_gpu_reset_timings(pme->gpu);
  72     }
  73 }
  74
  75 void pme_gpu_get_timings(const gmx_pme_t *pme, gmx_wallclock_gpu_pme_t *timings)
  76 {
  77     if (pme_gpu_active(pme))
  78     {
  79         pme_gpu_get_timings(pme->gpu, timings);
  80     }
  81 }
  82
  83 /*! \brief
  84  * A convenience wrapper for launching either the GPU or CPU FFT.
  85  *
  86  * \param[in] pme            The PME structure.
  87  * \param[in] gridIndex      The grid index - should currently always be 0.
  88  * \param[in] dir            The FFT direction enum.
  89  * \param[in] wcycle         The wallclock counter.
  90  */
  91 void inline parallel_3dfft_execute_gpu_wrapper(gmx_pme_t              *pme,
  92                                                const int               gridIndex,
  93                                                enum gmx_fft_direction  dir,
  94                                                gmx_wallcycle_t         wcycle)
  95 {
  96     GMX_ASSERT(gridIndex == 0, "Only single grid supported");
  97     if (pme_gpu_performs_FFT(pme->gpu))
  98     {
  99         wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 100         wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 101         pme_gpu_3dfft(pme->gpu, dir, gridIndex);
 102         wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 103         wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 104     }
 105     else
 106     {
 107         wallcycle_start(wcycle, ewcPME_FFT_MIXED_MODE);
 108 #pragma omp parallel for num_threads(pme->nthread) schedule(static)
 109         for (int thread = 0; thread < pme->nthread; thread++)
 110         {
 111             gmx_parallel_3dfft_execute(pme->pfft_setup[gridIndex], dir, thread, wcycle);
 112         }
 113         wallcycle_stop(wcycle, ewcPME_FFT_MIXED_MODE);
 114     }
 115 }
 116
 117 /* The PME computation code split into a few separate functions. */
 118
 119 void pme_gpu_prepare_computation(gmx_pme_t            *pme,
 120                                  bool                  needToUpdateBox,
 121                                  const matrix          box,
 122                                  gmx_wallcycle        *wcycle,
 123                                  int                   flags)
 124 {
 125     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 126     GMX_ASSERT(pme->nnodes > 0, "");
 127     GMX_ASSERT(pme->nnodes == 1 || pme->ndecompdim > 0, "");
 128
 129     PmeGpu *pmeGpu = pme->gpu;
 130     pmeGpu->settings.currentFlags = flags;
 131     // TODO these flags are only here to honor the CPU PME code, and probably should be removed
 132
 133     bool shouldUpdateBox = false;
 134     for (int i = 0; i < DIM; ++i)
 135     {
 136         for (int j = 0; j <= i; ++j)
 137         {
 138             shouldUpdateBox                  |= (pmeGpu->common->previousBox[i][j] != box[i][j]);
 139             pmeGpu->common->previousBox[i][j] = box[i][j];
 140         }
 141     }
 142
 143     if (needToUpdateBox || shouldUpdateBox) // || is to make the first computation always update
 144     {
 145         wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 146         wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 147         pme_gpu_update_input_box(pmeGpu, box);
 148         wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 149         wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 150
 151         if (!pme_gpu_performs_solve(pmeGpu))
 152         {
 153             // TODO remove code duplication and add test coverage
 154             matrix scaledBox;
 155             pmeGpu->common->boxScaler->scaleBox(box, scaledBox);
 156             gmx::invertBoxMatrix(scaledBox, pme->recipbox);
 157             pme->boxVolume = scaledBox[XX][XX] * scaledBox[YY][YY] * scaledBox[ZZ][ZZ];
 158         }
 159     }
 160 }
 161
 162
 163 void pme_gpu_launch_spread(gmx_pme_t            *pme,
 164                            const rvec           *x,
 165                            gmx_wallcycle        *wcycle)
 166 {
 167     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 168
 169     PmeGpu *pmeGpu = pme->gpu;
 170
 171     // The only spot of PME GPU where LAUNCH_GPU counter increases call-count
 172     wallcycle_start(wcycle, ewcLAUNCH_GPU);
 173     // The only spot of PME GPU where ewcsLAUNCH_GPU_PME subcounter increases call-count
 174     wallcycle_sub_start(wcycle, ewcsLAUNCH_GPU_PME);
 175     pme_gpu_copy_input_coordinates(pmeGpu, x);
 176     wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 177     wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 178
 179     const unsigned int gridIndex  = 0;
 180     real              *fftgrid    = pme->fftgrid[gridIndex];
 181     if (pmeGpu->settings.currentFlags & GMX_PME_SPREAD)
 182     {
 183         /* Spread the coefficients on a grid */
 184         const bool computeSplines = true;
 185         const bool spreadCharges  = true;
 186         wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 187         wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 188         pme_gpu_spread(pmeGpu, gridIndex, fftgrid, computeSplines, spreadCharges);
 189         wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 190         wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 191     }
 192 }
 193
 194 void pme_gpu_launch_complex_transforms(gmx_pme_t      *pme,
 195                                        gmx_wallcycle  *wcycle)
 196 {
 197     PmeGpu            *pmeGpu                 = pme->gpu;
 198     const bool         computeEnergyAndVirial = (pmeGpu->settings.currentFlags & GMX_PME_CALC_ENER_VIR) != 0;
 199     const bool         performBackFFT         = (pmeGpu->settings.currentFlags & (GMX_PME_CALC_F | GMX_PME_CALC_POT)) != 0;
 200     const unsigned int gridIndex              = 0;
 201     t_complex         *cfftgrid               = pme->cfftgrid[gridIndex];
 202
 203     if (pmeGpu->settings.currentFlags & GMX_PME_SPREAD)
 204     {
 205         if (!pme_gpu_performs_FFT(pmeGpu))
 206         {
 207             wallcycle_start(wcycle, ewcWAIT_GPU_PME_SPREAD);
 208             pme_gpu_sync_spread_grid(pme->gpu);
 209             wallcycle_stop(wcycle, ewcWAIT_GPU_PME_SPREAD);
 210         }
 211     }
 212
 213     try
 214     {
 215         if (pmeGpu->settings.currentFlags & GMX_PME_SOLVE)
 216         {
 217             /* do R2C 3D-FFT */
 218             parallel_3dfft_execute_gpu_wrapper(pme, gridIndex, GMX_FFT_REAL_TO_COMPLEX, wcycle);
 219
 220             /* solve in k-space for our local cells */
 221             if (pme_gpu_performs_solve(pmeGpu))
 222             {
 223                 const auto gridOrdering = pme_gpu_uses_dd(pmeGpu) ? GridOrdering::YZX : GridOrdering::XYZ;
 224                 wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 225                 wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 226                 pme_gpu_solve(pmeGpu, cfftgrid, gridOrdering, computeEnergyAndVirial);
 227                 wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 228                 wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 229             }
 230             else
 231             {
 232                 wallcycle_start(wcycle, ewcPME_SOLVE_MIXED_MODE);
 233 #pragma omp parallel for num_threads(pme->nthread) schedule(static)
 234                 for (int thread = 0; thread < pme->nthread; thread++)
 235                 {
 236                     solve_pme_yzx(pme, cfftgrid, pme->boxVolume,
 237                                   computeEnergyAndVirial, pme->nthread, thread);
 238                 }
 239                 wallcycle_stop(wcycle, ewcPME_SOLVE_MIXED_MODE);
 240             }
 241         }
 242
 243         if (performBackFFT)
 244         {
 245             parallel_3dfft_execute_gpu_wrapper(pme, gridIndex, GMX_FFT_COMPLEX_TO_REAL, wcycle);
 246         }
 247     } GMX_CATCH_ALL_AND_EXIT_WITH_FATAL_ERROR;
 248 }
 249
 250 void pme_gpu_launch_gather(const gmx_pme_t                 *pme,
 251                            gmx_wallcycle gmx_unused        *wcycle,
 252                            PmeForceOutputHandling           forceTreatment)
 253 {
 254     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 255
 256     if (!pme_gpu_performs_gather(pme->gpu))
 257     {
 258         return;
 259     }
 260
 261     wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 262     wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 263     const unsigned int gridIndex  = 0;
 264     real              *fftgrid    = pme->fftgrid[gridIndex];
 265     pme_gpu_gather(pme->gpu, forceTreatment, reinterpret_cast<float *>(fftgrid));
 266     wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 267     wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 268 }
 269
 270 //! Accumulate the \c forcesToAdd to \c f, using the available threads.
 271 static void sum_forces(gmx::ArrayRef<gmx::RVec>       f,
 272                        gmx::ArrayRef<const gmx::RVec> forceToAdd)
 273 {
 274     const int      end = forceToAdd.size();
 275
 276     int gmx_unused nt = gmx_omp_nthreads_get(emntPME);
 277 #pragma omp parallel for num_threads(nt) schedule(static)
 278     for (int i = 0; i < end; i++)
 279     {
 280         f[i] += forceToAdd[i];
 281     }
 282 }
 283
 284 //! Reduce quantities from \c output to \c forceWithVirial and \c enerd.
 285 static void pme_gpu_reduce_outputs(const int             flags,
 286                                    const PmeOutput      &output,
 287                                    gmx_wallcycle        *wcycle,
 288                                    gmx::ForceWithVirial *forceWithVirial,
 289                                    gmx_enerdata_t       *enerd)
 290 {
 291     wallcycle_start(wcycle, ewcPME_GPU_F_REDUCTION);
 292     GMX_ASSERT(forceWithVirial, "Invalid force pointer");
 293     const bool haveComputedEnergyAndVirial = (flags & GMX_PME_CALC_ENER_VIR) != 0;
 294     if (haveComputedEnergyAndVirial)
 295     {
 296         GMX_ASSERT(enerd, "Invalid energy output manager");
 297         forceWithVirial->addVirialContribution(output.coulombVirial_);
 298         enerd->term[F_COUL_RECIP] += output.coulombEnergy_;
 299     }
 300     sum_forces(forceWithVirial->force_, output.forces_);
 301     wallcycle_stop(wcycle, ewcPME_GPU_F_REDUCTION);
 302 }
 303
 304 bool pme_gpu_try_finish_task(gmx_pme_t            *pme,
 305                              const int             flags,
 306                              gmx_wallcycle        *wcycle,
 307                              gmx::ForceWithVirial *forceWithVirial,
 308                              gmx_enerdata_t       *enerd,
 309                              GpuTaskCompletion     completionKind)
 310 {
 311     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 312
 313     // First, if possible, check whether all tasks on the stream have
 314     // completed, and return fast if not. Accumulate to wcycle the
 315     // time needed for that checking, but do not yet record that the
 316     // gather has occured.
 317     bool           needToSynchronize      = true;
 318     constexpr bool c_streamQuerySupported = (GMX_GPU == GMX_GPU_CUDA);
 319     // TODO: implement c_streamQuerySupported with an additional GpuEventSynchronizer per stream (#2521)
 320     if ((completionKind == GpuTaskCompletion::Check) && c_streamQuerySupported)
 321     {
 322         wallcycle_start_nocount(wcycle, ewcWAIT_GPU_PME_GATHER);
 323         // Query the PME stream for completion of all tasks enqueued and
 324         // if we're not done, stop the timer before early return.
 325         const bool pmeGpuDone = pme_gpu_stream_query(pme->gpu);
 326         wallcycle_stop(wcycle, ewcWAIT_GPU_PME_GATHER);
 327
 328         if (!pmeGpuDone)
 329         {
 330             return false;
 331         }
 332         needToSynchronize = false;
 333     }
 334
 335     wallcycle_start(wcycle, ewcWAIT_GPU_PME_GATHER);
 336     // If the above check passed, then there is no need to make an
 337     // explicit synchronization call.
 338     if (needToSynchronize)
 339     {
 340         // Synchronize the whole PME stream at once, including D2H result transfers.
 341         pme_gpu_synchronize(pme->gpu);
 342     }
 343     pme_gpu_update_timings(pme->gpu);
 344     PmeOutput output = pme_gpu_getOutput(*pme, flags);
 345     wallcycle_stop(wcycle, ewcWAIT_GPU_PME_GATHER);
 346
 347     pme_gpu_reduce_outputs(flags, output, wcycle, forceWithVirial, enerd);
 348
 349     return true;
 350 }
 351
 352 // This is used by PME-only ranks
 353 PmeOutput pme_gpu_wait_finish_task(gmx_pme_t     *pme,
 354                                    const int      flags,
 355                                    gmx_wallcycle *wcycle)
 356 {
 357     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 358
 359     wallcycle_start(wcycle, ewcWAIT_GPU_PME_GATHER);
 360     // Synchronize the whole PME stream at once, including D2H result transfers.
 361     pme_gpu_synchronize(pme->gpu);
 362
 363     pme_gpu_update_timings(pme->gpu);
 364     PmeOutput output = pme_gpu_getOutput(*pme, flags);
 365     wallcycle_stop(wcycle, ewcWAIT_GPU_PME_GATHER);
 366     return output;
 367 }
 368
 369 // This is used when not using the alternate-waiting reduction
 370 void pme_gpu_wait_and_reduce(gmx_pme_t            *pme,
 371                              const int             flags,
 372                              gmx_wallcycle        *wcycle,
 373                              gmx::ForceWithVirial *forceWithVirial,
 374                              gmx_enerdata_t       *enerd)
 375 {
 376     PmeOutput output = pme_gpu_wait_finish_task(pme, flags, wcycle);
 377     pme_gpu_reduce_outputs(flags, output, wcycle, forceWithVirial, enerd);
 378 }
 379
 380 void pme_gpu_reinit_computation(const gmx_pme_t *pme,
 381                                 gmx_wallcycle   *wcycle)
 382 {
 383     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 384
 385     wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 386     wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 387
 388     pme_gpu_clear_grids(pme->gpu);
 389     pme_gpu_clear_energy_virial(pme->gpu);
 390
 391     wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 392     wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 393 }