src/gromacs/ewald/pme_gpu.cpp

   1 /*
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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 int pme_gpu_get_padding_size(const gmx_pme_t* pme)
  84 {
  85
  86     if (!pme || !pme_gpu_active(pme))
  87     {
  88         return 0;
  89     }
  90     else
  91     {
  92         return pme_gpu_get_atom_data_alignment(pme->gpu);
  93     }
  94 }
  95
  96 /*! \brief
  97  * A convenience wrapper for launching either the GPU or CPU FFT.
  98  *
  99  * \param[in] pme            The PME structure.
 100  * \param[in] gridIndex      The grid index - should currently always be 0.
 101  * \param[in] dir            The FFT direction enum.
 102  * \param[in] wcycle         The wallclock counter.
 103  */
 104 void inline parallel_3dfft_execute_gpu_wrapper(gmx_pme_t*             pme,
 105                                                const int              gridIndex,
 106                                                enum gmx_fft_direction dir,
 107                                                gmx_wallcycle_t        wcycle)
 108 {
 109     GMX_ASSERT(gridIndex == 0, "Only single grid supported");
 110     if (pme_gpu_performs_FFT(pme->gpu))
 111     {
 112         wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 113         wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 114         pme_gpu_3dfft(pme->gpu, dir, gridIndex);
 115         wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 116         wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 117     }
 118     else
 119     {
 120         wallcycle_start(wcycle, ewcPME_FFT_MIXED_MODE);
 121 #pragma omp parallel for num_threads(pme->nthread) schedule(static)
 122         for (int thread = 0; thread < pme->nthread; thread++)
 123         {
 124             gmx_parallel_3dfft_execute(pme->pfft_setup[gridIndex], dir, thread, wcycle);
 125         }
 126         wallcycle_stop(wcycle, ewcPME_FFT_MIXED_MODE);
 127     }
 128 }
 129
 130 /* The PME computation code split into a few separate functions. */
 131
 132 void pme_gpu_prepare_computation(gmx_pme_t*     pme,
 133                                  bool           needToUpdateBox,
 134                                  const matrix   box,
 135                                  gmx_wallcycle* wcycle,
 136                                  int            flags,
 137                                  bool           useGpuForceReduction)
 138 {
 139     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 140     GMX_ASSERT(pme->nnodes > 0, "");
 141     GMX_ASSERT(pme->nnodes == 1 || pme->ndecompdim > 0, "");
 142
 143     PmeGpu* pmeGpu                = pme->gpu;
 144     pmeGpu->settings.currentFlags = flags;
 145     // TODO these flags are only here to honor the CPU PME code, and probably should be removed
 146     pmeGpu->settings.useGpuForceReduction = useGpuForceReduction;
 147
 148     bool shouldUpdateBox = false;
 149     for (int i = 0; i < DIM; ++i)
 150     {
 151         for (int j = 0; j <= i; ++j)
 152         {
 153             shouldUpdateBox |= (pmeGpu->common->previousBox[i][j] != box[i][j]);
 154             pmeGpu->common->previousBox[i][j] = box[i][j];
 155         }
 156     }
 157
 158     if (needToUpdateBox || shouldUpdateBox) // || is to make the first computation always update
 159     {
 160         wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 161         wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 162         pme_gpu_update_input_box(pmeGpu, box);
 163         wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 164         wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 165
 166         if (!pme_gpu_performs_solve(pmeGpu))
 167         {
 168             // TODO remove code duplication and add test coverage
 169             matrix scaledBox;
 170             pmeGpu->common->boxScaler->scaleBox(box, scaledBox);
 171             gmx::invertBoxMatrix(scaledBox, pme->recipbox);
 172             pme->boxVolume = scaledBox[XX][XX] * scaledBox[YY][YY] * scaledBox[ZZ][ZZ];
 173         }
 174     }
 175 }
 176
 177 void pme_gpu_launch_spread(gmx_pme_t* pme, GpuEventSynchronizer* xReadyOnDevice, gmx_wallcycle* wcycle)
 178 {
 179     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 180     GMX_ASSERT(xReadyOnDevice || !pme->bPPnode || (GMX_GPU != GMX_GPU_CUDA),
 181                "Need a valid xReadyOnDevice on PP+PME ranks with CUDA.");
 182
 183     PmeGpu* pmeGpu = pme->gpu;
 184
 185     const unsigned int gridIndex = 0;
 186     real*              fftgrid   = pme->fftgrid[gridIndex];
 187     if (pmeGpu->settings.currentFlags & GMX_PME_SPREAD)
 188     {
 189         /* Spread the coefficients on a grid */
 190         const bool computeSplines = true;
 191         const bool spreadCharges  = true;
 192         wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 193         wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 194         pme_gpu_spread(pmeGpu, xReadyOnDevice, gridIndex, fftgrid, computeSplines, spreadCharges);
 195         wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 196         wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 197     }
 198 }
 199
 200 void pme_gpu_launch_complex_transforms(gmx_pme_t* pme, gmx_wallcycle* wcycle)
 201 {
 202     PmeGpu*    pmeGpu                 = pme->gpu;
 203     const bool computeEnergyAndVirial = (pmeGpu->settings.currentFlags & GMX_PME_CALC_ENER_VIR) != 0;
 204     const bool performBackFFT = (pmeGpu->settings.currentFlags & (GMX_PME_CALC_F | GMX_PME_CALC_POT)) != 0;
 205     const unsigned int gridIndex = 0;
 206     t_complex*         cfftgrid  = pme->cfftgrid[gridIndex];
 207
 208     if (pmeGpu->settings.currentFlags & GMX_PME_SPREAD)
 209     {
 210         if (!pme_gpu_performs_FFT(pmeGpu))
 211         {
 212             wallcycle_start(wcycle, ewcWAIT_GPU_PME_SPREAD);
 213             pme_gpu_sync_spread_grid(pme->gpu);
 214             wallcycle_stop(wcycle, ewcWAIT_GPU_PME_SPREAD);
 215         }
 216     }
 217
 218     try
 219     {
 220         if (pmeGpu->settings.currentFlags & GMX_PME_SOLVE)
 221         {
 222             /* do R2C 3D-FFT */
 223             parallel_3dfft_execute_gpu_wrapper(pme, gridIndex, GMX_FFT_REAL_TO_COMPLEX, wcycle);
 224
 225             /* solve in k-space for our local cells */
 226             if (pme_gpu_performs_solve(pmeGpu))
 227             {
 228                 const auto gridOrdering = pme_gpu_uses_dd(pmeGpu) ? GridOrdering::YZX : GridOrdering::XYZ;
 229                 wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 230                 wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 231                 pme_gpu_solve(pmeGpu, cfftgrid, gridOrdering, computeEnergyAndVirial);
 232                 wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 233                 wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 234             }
 235             else
 236             {
 237                 wallcycle_start(wcycle, ewcPME_SOLVE_MIXED_MODE);
 238 #pragma omp parallel for num_threads(pme->nthread) schedule(static)
 239                 for (int thread = 0; thread < pme->nthread; thread++)
 240                 {
 241                     solve_pme_yzx(pme, cfftgrid, pme->boxVolume, computeEnergyAndVirial,
 242                                   pme->nthread, thread);
 243                 }
 244                 wallcycle_stop(wcycle, ewcPME_SOLVE_MIXED_MODE);
 245             }
 246         }
 247
 248         if (performBackFFT)
 249         {
 250             parallel_3dfft_execute_gpu_wrapper(pme, gridIndex, GMX_FFT_COMPLEX_TO_REAL, wcycle);
 251         }
 252     }
 253     GMX_CATCH_ALL_AND_EXIT_WITH_FATAL_ERROR;
 254 }
 255
 256 void pme_gpu_launch_gather(const gmx_pme_t* pme, gmx_wallcycle gmx_unused* wcycle, PmeForceOutputHandling forceTreatment)
 257 {
 258     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 259
 260     if (!pme_gpu_performs_gather(pme->gpu))
 261     {
 262         return;
 263     }
 264
 265     wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 266     wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 267     const unsigned int gridIndex = 0;
 268     real*              fftgrid   = pme->fftgrid[gridIndex];
 269     pme_gpu_gather(pme->gpu, forceTreatment, reinterpret_cast<float*>(fftgrid));
 270     wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 271     wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 272 }
 273
 274 //! Accumulate the \c forcesToAdd to \c f, using the available threads.
 275 static void sum_forces(gmx::ArrayRef<gmx::RVec> f, gmx::ArrayRef<const gmx::RVec> forceToAdd)
 276 {
 277     const int end = forceToAdd.size();
 278
 279     int gmx_unused nt = gmx_omp_nthreads_get(emntPME);
 280 #pragma omp parallel for num_threads(nt) schedule(static)
 281     for (int i = 0; i < end; i++)
 282     {
 283         f[i] += forceToAdd[i];
 284     }
 285 }
 286
 287 //! Reduce quantities from \c output to \c forceWithVirial and \c enerd.
 288 static void pme_gpu_reduce_outputs(const int             flags,
 289                                    const PmeOutput&      output,
 290                                    gmx_wallcycle*        wcycle,
 291                                    gmx::ForceWithVirial* forceWithVirial,
 292                                    gmx_enerdata_t*       enerd)
 293 {
 294     wallcycle_start(wcycle, ewcPME_GPU_F_REDUCTION);
 295     GMX_ASSERT(forceWithVirial, "Invalid force pointer");
 296
 297     const bool haveComputedEnergyAndVirial = (flags & GMX_PME_CALC_ENER_VIR) != 0;
 298     if (haveComputedEnergyAndVirial)
 299     {
 300         GMX_ASSERT(enerd, "Invalid energy output manager");
 301         forceWithVirial->addVirialContribution(output.coulombVirial_);
 302         enerd->term[F_COUL_RECIP] += output.coulombEnergy_;
 303     }
 304     if (output.haveForceOutput_)
 305     {
 306         sum_forces(forceWithVirial->force_, output.forces_);
 307     }
 308     wallcycle_stop(wcycle, ewcPME_GPU_F_REDUCTION);
 309 }
 310
 311 bool pme_gpu_try_finish_task(gmx_pme_t*            pme,
 312                              const int             flags,
 313                              gmx_wallcycle*        wcycle,
 314                              gmx::ForceWithVirial* forceWithVirial,
 315                              gmx_enerdata_t*       enerd,
 316                              GpuTaskCompletion     completionKind)
 317 {
 318     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 319     GMX_ASSERT(!pme->gpu->settings.useGpuForceReduction,
 320                "GPU force reduction should not be active on the pme_gpu_try_finish_task() path");
 321
 322     // First, if possible, check whether all tasks on the stream have
 323     // completed, and return fast if not. Accumulate to wcycle the
 324     // time needed for that checking, but do not yet record that the
 325     // gather has occured.
 326     bool           needToSynchronize      = true;
 327     constexpr bool c_streamQuerySupported = (GMX_GPU == GMX_GPU_CUDA);
 328     // TODO: implement c_streamQuerySupported with an additional GpuEventSynchronizer per stream (#2521)
 329     if ((completionKind == GpuTaskCompletion::Check) && c_streamQuerySupported)
 330     {
 331         wallcycle_start_nocount(wcycle, ewcWAIT_GPU_PME_GATHER);
 332         // Query the PME stream for completion of all tasks enqueued and
 333         // if we're not done, stop the timer before early return.
 334         const bool pmeGpuDone = pme_gpu_stream_query(pme->gpu);
 335         wallcycle_stop(wcycle, ewcWAIT_GPU_PME_GATHER);
 336
 337         if (!pmeGpuDone)
 338         {
 339             return false;
 340         }
 341         needToSynchronize = false;
 342     }
 343
 344     wallcycle_start(wcycle, ewcWAIT_GPU_PME_GATHER);
 345     // If the above check passed, then there is no need to make an
 346     // explicit synchronization call.
 347     if (needToSynchronize)
 348     {
 349         // Synchronize the whole PME stream at once, including D2H result transfers.
 350         pme_gpu_synchronize(pme->gpu);
 351     }
 352     pme_gpu_update_timings(pme->gpu);
 353     PmeOutput output = pme_gpu_getOutput(*pme, flags);
 354     wallcycle_stop(wcycle, ewcWAIT_GPU_PME_GATHER);
 355
 356     GMX_ASSERT(pme->gpu->settings.useGpuForceReduction == !output.haveForceOutput_,
 357                "When forces are reduced on the CPU, there needs to be force output");
 358     pme_gpu_reduce_outputs(flags, output, wcycle, forceWithVirial, enerd);
 359
 360     return true;
 361 }
 362
 363 // This is used by PME-only ranks
 364 PmeOutput pme_gpu_wait_finish_task(gmx_pme_t* pme, const int flags, gmx_wallcycle* wcycle)
 365 {
 366     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 367
 368     wallcycle_start(wcycle, ewcWAIT_GPU_PME_GATHER);
 369
 370     // Synchronize the whole PME stream at once, including D2H result transfers
 371     // if there are outputs we need to wait for at this step; we still call getOutputs
 372     // for uniformity and because it sets the PmeOutput.haveForceOutput_.
 373     const bool haveComputedEnergyAndVirial = (flags & GMX_PME_CALC_ENER_VIR) != 0;
 374     if (!pme->gpu->settings.useGpuForceReduction || haveComputedEnergyAndVirial)
 375     {
 376         pme_gpu_synchronize(pme->gpu);
 377     }
 378
 379     PmeOutput output = pme_gpu_getOutput(*pme, flags);
 380     wallcycle_stop(wcycle, ewcWAIT_GPU_PME_GATHER);
 381     return output;
 382 }
 383
 384 // This is used when not using the alternate-waiting reduction
 385 void pme_gpu_wait_and_reduce(gmx_pme_t*            pme,
 386                              const int             flags,
 387                              gmx_wallcycle*        wcycle,
 388                              gmx::ForceWithVirial* forceWithVirial,
 389                              gmx_enerdata_t*       enerd)
 390 {
 391     PmeOutput output = pme_gpu_wait_finish_task(pme, flags, wcycle);
 392     GMX_ASSERT(pme->gpu->settings.useGpuForceReduction == !output.haveForceOutput_,
 393                "When forces are reduced on the CPU, there needs to be force output");
 394     pme_gpu_reduce_outputs(flags, output, wcycle, forceWithVirial, enerd);
 395 }
 396
 397 void pme_gpu_reinit_computation(const gmx_pme_t* pme, gmx_wallcycle* wcycle)
 398 {
 399     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 400
 401     wallcycle_start_nocount(wcycle, ewcLAUNCH_GPU);
 402     wallcycle_sub_start_nocount(wcycle, ewcsLAUNCH_GPU_PME);
 403
 404     pme_gpu_update_timings(pme->gpu);
 405
 406     pme_gpu_clear_grids(pme->gpu);
 407     pme_gpu_clear_energy_virial(pme->gpu);
 408
 409     wallcycle_sub_stop(wcycle, ewcsLAUNCH_GPU_PME);
 410     wallcycle_stop(wcycle, ewcLAUNCH_GPU);
 411 }
 412
 413 DeviceBuffer<float> pme_gpu_get_device_x(const gmx_pme_t* pme)
 414 {
 415     GMX_ASSERT((pme && pme_gpu_active(pme)),
 416                "PME GPU coordinates buffer was requested from uninitialized PME module");
 417     return pme_gpu_get_kernelparam_coordinates(pme->gpu);
 418 }
 419
 420 void* pme_gpu_get_device_f(const gmx_pme_t* pme)
 421 {
 422     if (!pme || !pme_gpu_active(pme))
 423     {
 424         return nullptr;
 425     }
 426     return pme_gpu_get_kernelparam_forces(pme->gpu);
 427 }
 428
 429 void pme_gpu_set_device_x(const gmx_pme_t* pme, DeviceBuffer<float> d_x)
 430 {
 431     GMX_ASSERT(pme != nullptr, "Null pointer is passed as a PME to the set coordinates function.");
 432     GMX_ASSERT(pme_gpu_active(pme), "This should be a GPU run of PME but it is not enabled.");
 433
 434     pme_gpu_set_kernelparam_coordinates(pme->gpu, d_x);
 435 }
 436
 437 void* pme_gpu_get_device_stream(const gmx_pme_t* pme)
 438 {
 439     if (!pme || !pme_gpu_active(pme))
 440     {
 441         return nullptr;
 442     }
 443     return pme_gpu_get_stream(pme->gpu);
 444 }
 445
 446 void* pme_gpu_get_device_context(const gmx_pme_t* pme)
 447 {
 448     if (!pme || !pme_gpu_active(pme))
 449     {
 450         return nullptr;
 451     }
 452     return pme_gpu_get_context(pme->gpu);
 453 }
 454
 455 GpuEventSynchronizer* pme_gpu_get_f_ready_synchronizer(const gmx_pme_t* pme)
 456 {
 457     if (!pme || !pme_gpu_active(pme))
 458     {
 459         return nullptr;
 460     }
 461
 462     return pme_gpu_get_forces_ready_synchronizer(pme->gpu);
 463 }