lattice-benchmarks/Quda/Benchmark_Quda.cpp

#include <algorithm>
#include <array>
#include <blas_quda.h>
#include <cassert>
#include <color_spinor_field.h>
#include <dirac_quda.h>
#include <gauge_tools.h>
#include <memory>
#include <mpi.h>
#include <stdio.h>
#include <stdlib.h>

using namespace quda;

// This is the MPI grid, i.e. the layout of ranks
int nranks = -1;
std::array<int, 4> mpi_grid = {1, 1, 1, 1};

void initComms(int argc, char **argv)
{
  // init MPI communication
  MPI_Init(&argc, &argv);

  MPI_Comm_size(MPI_COMM_WORLD, &nranks);
  assert(1 <= nranks && nranks <= 100000);

  mpi_grid[3] = nranks;

  // this maps coordinates to rank number
  auto lex_rank_from_coords = [](int const *coords, void *)
  {
    int rank = coords[0];
    for (int i = 1; i < 4; i++)
      rank = mpi_grid[i] * rank + coords[i];
    return rank;
  };

  initCommsGridQuda(4, mpi_grid.data(), lex_rank_from_coords, nullptr);

  for (int d = 0; d < 4; d++)
    if (mpi_grid[d] > 1)
      commDimPartitionedSet(d);
}

// creates a random gauge field. L = local(!) size
cudaGaugeField make_gauge_field(int L)
{
  GaugeFieldParam param;

  // dimension and type of the lattice object
  param.nDim = 4;
  param.x[0] = L;
  param.x[1] = L;
  param.x[2] = L;
  param.x[3] = L;

  // number of colors. potentially confusingly, QUDA sometimes uses the word "color" to
  // things unrelated with physical color. things like "nColor=32" do pop up in deflation
  // solvers where it (to my understanding) refers to the number of (parallely processed)
  // deflation vectors.
  param.nColor = 3;

  // boundary conditions (dont really care for benchmark)
  param.t_boundary = QUDA_PERIODIC_T;

  // for this benchmark we only need "SINGLE" and/or "DOUBLE" precision. But smaller
  // precisions are available in QUDA too
  param.setPrecision(QUDA_DOUBLE_PRECISION);

  // no even/odd subset, we want a full lattice
  param.siteSubset = QUDA_FULL_SITE_SUBSET;

  // what kind of 3x3 matrices the field contains. A proper gauge field has SU(3)
  // matrices, but (for example) smeared/thick links could have non-unitary links.
  param.link_type = QUDA_SU3_LINKS;

  // "NULL" does not initialize the field upon creation, "ZERO" would set everything to 0
  param.create = QUDA_NULL_FIELD_CREATE;

  // field should be allocated directly on the accelerator/GPU
  param.location = QUDA_CUDA_FIELD_LOCATION;

  // "reconstruct" here means reconstructing a SU(3) matrix from fewer than 18 real
  // numbers (=3x3 complex numbers). Great feature in production (saving
  // memory/cache/network bandwidth), not used for this benchmark.
  param.reconstruct = QUDA_RECONSTRUCT_NO;

  // "ghostExchange" would often be called "halo exchange" outside of Quda. This has
  // nothing to do with ghost fields from continuum/perturbative qcd.
  param.ghostExchange = QUDA_GHOST_EXCHANGE_NO;

  // This controls the physical order of elements. "float2" is the the default
  param.order = QUDA_FLOAT2_GAUGE_ORDER;

  // this means the field is a LORENTZ vector (which a gauge field must be). Has nothing
  // to do with spin.
  param.geometry = QUDA_VECTOR_GEOMETRY;

  // create the field and fill with random SU(3) matrices
  // std::cout << param << std::endl; // double-check parameters
  auto U = cudaGaugeField(param);
  gaugeGauss(U, /*seed=*/1234, 1.0);
  return U;
}

// create a random source vector (L = local size)
ColorSpinorField make_source(int L)
{
  ColorSpinorParam param;
  param.nColor = 3;
  param.nSpin = 4;
  param.nVec = 1; // only a single vector
  param.pad = 0;
  param.siteSubset = QUDA_FULL_SITE_SUBSET;
  param.nDim = 4;
  param.x[0] = L;
  param.x[1] = L;
  param.x[2] = L;
  param.x[3] = L;
  param.x[4] = 1; // no fifth dimension
  param.pc_type = QUDA_4D_PC;
  param.siteOrder = QUDA_EVEN_ODD_SITE_ORDER;
  param.gammaBasis = QUDA_DEGRAND_ROSSI_GAMMA_BASIS;
  param.create = QUDA_NULL_FIELD_CREATE; // do not (zero-) initilize the field
  param.setPrecision(QUDA_DOUBLE_PRECISION);
  param.location = QUDA_CUDA_FIELD_LOCATION;

  // create the field and fill it with random values
  auto src = ColorSpinorField(param);
  quda::RNG rng(src, 1234);
  spinorNoise(src, rng, QUDA_NOISE_GAUSS);
  /*printfQuda(
      "created src with norm = %f (sanity check: should be close to %f) and %f bytes\n",
      blas::norm2(src), 2.0 * 12 * geom[0] * geom[1] * geom[2] * geom[3],
      src.Bytes() * 1.0);*/
  // src.PrintDims();

  return src;
}

void benchmark_wilson()
{
  int niter = 20;
  int niter_warmup = 10;

  printfQuda("==================== wilson dirac operator ====================\n");
  printfQuda("IMPORTANT: QUDAs own flop counting. Probably not the same as in Grid.\n");
  printfQuda("%5s %15s %15s\n", "L", "time (usec)", "Gflop/s/rank");

  for (int L : {8, 12, 16, 24, 32})
  {
    auto U = make_gauge_field(L);
    auto src = make_source(L);

    // create (Wilson) dirac operator
    DiracParam param;
    param.kappa = 0.10;
    param.dagger = QUDA_DAG_NO;
    param.matpcType = QUDA_MATPC_EVEN_EVEN;
    auto dirac = DiracWilson(param);

    // insert gauge field into the dirac operator
    // (the additional nullptr's are for smeared links and fancy preconditioners and such.
    // Not used for simple Wilson fermions)
    dirac.updateFields(&U, nullptr, nullptr, nullptr);

    auto tmp = ColorSpinorField(ColorSpinorParam(src));

    // couple iterations without timing to warm up
    for (int iter = 0; iter < niter_warmup; ++iter)
      dirac.M(tmp, src);

    // actual benchmark with timings
    dirac.Flops(); // reset flops counter
    device_timer_t device_timer;
    device_timer.start();
    for (int iter = 0; iter < niter; ++iter)
      dirac.M(tmp, src);
    device_timer.stop();

    double secs = device_timer.last() / niter;
    double flops = 1.0 * dirac.Flops() / niter;

    printfQuda("%5d %15.2f %15.2f\n", L, secs * 1e6, flops / secs * 1e-9);
  }
}

void benchmark_axpy()
{
  // number of iterations for warmup / measurement
  // (feel free to change for noise/time tradeoff)
  constexpr int niter_warmup = 10;
  constexpr int niter = 20;

  printfQuda("==================== axpy / memory ====================\n");

  ColorSpinorParam param;
  param.nDim = 4;   // 4-dimensional lattice
  param.x[4] = 1;   // no fifth dimension
  param.nColor = 3; // supported values for nSpin/nColor are configured when compiling
                    // QUDA. "3*4" will probably always be enabled, so we stick with this
  param.nSpin = 4;
  param.nVec = 1;                            // just a single vector
  param.siteSubset = QUDA_FULL_SITE_SUBSET;  // full lattice = no odd/even
  param.pad = 0;                             // no padding
  param.create = QUDA_NULL_FIELD_CREATE;     // do not (zero-) initilize the field
  param.location = QUDA_CUDA_FIELD_LOCATION; // field should reside on GPU
  param.setPrecision(QUDA_DOUBLE_PRECISION);

  // the following dont matter for an axpy benchmark, but need to choose something
  param.pc_type = QUDA_4D_PC;
  param.siteOrder = QUDA_EVEN_ODD_SITE_ORDER;
  param.gammaBasis = QUDA_DEGRAND_ROSSI_GAMMA_BASIS;

  printfQuda("%5s %15s %15s %15s %15s\n", "L", "size (MiB/rank)", "time (usec)",
             "GiB/s/rank", "Gflop/s/rank");
  std::vector L_list = {8, 12, 16, 24, 32};
  for (int L : L_list)
  {
    // IMPORTANT: all of `param.x`, `field_elements`, `field.Bytes()`
    //            are LOCAL, i.e. per rank / per GPU

    param.x[0] = L;
    param.x[1] = L;
    param.x[2] = L;
    param.x[3] = L;

    // number of (real) elements in one (local) field
    size_t field_elements = 2 * param.x[0] * param.x[1] * param.x[2] * param.x[3] *
                            param.nColor * param.nSpin;

    // create the field(s)
    auto fieldA = ColorSpinorField(param);
    auto fieldB = ColorSpinorField(param);
    assert(fieldA.Bytes() == sizeof(double) * field_elements); // sanity check
    assert(fieldB.Bytes() == sizeof(double) * field_elements); // sanity check

    // fill fields with random values
    quda::RNG rng(fieldA, 1234);
    spinorNoise(fieldA, rng, QUDA_NOISE_GAUSS);
    spinorNoise(fieldB, rng, QUDA_NOISE_GAUSS);

    // number of operations / bytes per iteration
    // axpy is one addition, one multiplication, two read, one write
    double flops = 2 * field_elements;
    double memory = 3 * sizeof(double) * field_elements;

    // do some iterations to to let QUDA do its internal tuning and also stabilize cache
    // behaviour and such
    for (int iter = 0; iter < niter_warmup; ++iter)
      blas::axpy(1.234, fieldA, fieldB);

    // running the actual benchmark
    device_timer_t device_timer;
    device_timer.start();
    for (int iter = 0; iter < niter; ++iter)
      blas::axpy(1.234, fieldA, fieldB);
    device_timer.stop();
    double secs = device_timer.last() / niter; // seconds per iteration

    printfQuda("%5d %15.2f %15.2f %15.2f %15.2f\n", L, memory / 1024. / 1024., secs * 1e6,
               memory / secs / 1024. / 1024. / 1024., flops / secs * 1e-9);
  }
}

int main(int argc, char **argv)
{
  initComms(argc, argv);

  initQuda(-1); // -1 for multi-gpu. otherwise this selects the device to be used

  //  verbosity options are:
  //  SILENT, SUMMARIZE, VERBOSE, DEBUG_VERBOSE
  setVerbosity(QUDA_SUMMARIZE);

  printfQuda("MPI layout = %d %d %d %d\n", mpi_grid[0], mpi_grid[1], mpi_grid[2],
             mpi_grid[3]);

  benchmark_axpy();

  setVerbosity(QUDA_SILENT);
  benchmark_wilson();
  setVerbosity(QUDA_SUMMARIZE);

  printfQuda("==================== done with all benchmarks ====================\n");
  endQuda();
  quda::comm_finalize();
  MPI_Finalize();
}