lammps/lib/kokkos/containers/performance_tests/TestGlobal2LocalIds.hpp

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#ifndef KOKKOS_TEST_GLOBAL_TO_LOCAL_IDS_HPP
#define KOKKOS_TEST_GLOBAL_TO_LOCAL_IDS_HPP

#include <Kokkos_Core.hpp>
#include <Kokkos_UnorderedMap.hpp>
#include <vector>
#include <algorithm>

#include <Kokkos_Timer.hpp>

// This test will simulate global ids

namespace Performance {

static const unsigned begin_id_size = 256u;
static const unsigned end_id_size   = 1u << 22;
static const unsigned id_step       = 2u;

union helper {
  uint32_t word;
  uint8_t byte[4];
};

template <typename Device>
struct generate_ids {
  using execution_space = Device;
  using size_type       = typename execution_space::size_type;
  using local_id_view   = Kokkos::View<uint32_t*, execution_space>;

  local_id_view local_2_global;

  generate_ids(local_id_view& ids) : local_2_global(ids) {
    Kokkos::parallel_for(local_2_global.extent(0), *this);
  }

  KOKKOS_INLINE_FUNCTION
  void operator()(size_type i) const {
    helper x = {static_cast<uint32_t>(i)};

    // shuffle the bytes of i to create a unique, semi-random global_id
    x.word = ~x.word;

    uint8_t tmp = x.byte[3];
    x.byte[3]   = x.byte[1];
    x.byte[1]   = tmp;

    tmp       = x.byte[2];
    x.byte[2] = x.byte[0];
    x.byte[0] = tmp;

    local_2_global[i] = x.word;
  }
};

template <typename Device>
struct fill_map {
  using execution_space = Device;
  using size_type       = typename execution_space::size_type;
  using local_id_view   = Kokkos::View<const uint32_t*, execution_space,
                                     Kokkos::MemoryRandomAccess>;
  using global_id_view =
      Kokkos::UnorderedMap<uint32_t, size_type, execution_space>;

  global_id_view global_2_local;
  local_id_view local_2_global;

  fill_map(global_id_view gIds, local_id_view lIds)
      : global_2_local(gIds), local_2_global(lIds) {
    Kokkos::parallel_for(local_2_global.extent(0), *this);
  }

  KOKKOS_INLINE_FUNCTION
  void operator()(size_type i) const {
    global_2_local.insert(local_2_global[i], i);
  }
};

template <typename Device>
struct find_test {
  using execution_space = Device;
  using size_type       = typename execution_space::size_type;
  using local_id_view   = Kokkos::View<const uint32_t*, execution_space,
                                     Kokkos::MemoryRandomAccess>;
  using global_id_view =
      Kokkos::UnorderedMap<const uint32_t, const size_type, execution_space>;

  global_id_view global_2_local;
  local_id_view local_2_global;

  using value_type = size_t;

  find_test(global_id_view gIds, local_id_view lIds, value_type& num_errors)
      : global_2_local(gIds), local_2_global(lIds) {
    Kokkos::parallel_reduce(local_2_global.extent(0), *this, num_errors);
  }

  KOKKOS_INLINE_FUNCTION
  void init(value_type& v) const { v = 0; }

  KOKKOS_INLINE_FUNCTION
  void join(volatile value_type& dst, volatile value_type const& src) const {
    dst += src;
  }

  KOKKOS_INLINE_FUNCTION
  void operator()(size_type i, value_type& num_errors) const {
    uint32_t index = global_2_local.find(local_2_global[i]);

    if (global_2_local.value_at(index) != i) ++num_errors;
  }
};

template <typename Device>
void test_global_to_local_ids(unsigned num_ids) {
  using execution_space = Device;
  using size_type       = typename execution_space::size_type;

  using local_id_view = Kokkos::View<uint32_t*, execution_space>;
  using global_id_view =
      Kokkos::UnorderedMap<uint32_t, size_type, execution_space>;

  // size
  std::cout << num_ids << ", ";

  double elasped_time = 0;
  Kokkos::Timer timer;

  local_id_view local_2_global("local_ids", num_ids);
  global_id_view global_2_local((3u * num_ids) / 2u);

  // create
  elasped_time = timer.seconds();
  std::cout << elasped_time << ", ";
  timer.reset();

  // generate unique ids
  { generate_ids<Device> gen(local_2_global); }
  Device().fence();
  // generate
  elasped_time = timer.seconds();
  std::cout << elasped_time << ", ";
  timer.reset();

  { fill_map<Device> fill(global_2_local, local_2_global); }
  Device().fence();

  // fill
  elasped_time = timer.seconds();
  std::cout << elasped_time << ", ";
  timer.reset();

  size_t num_errors = 0;
  for (int i = 0; i < 100; ++i) {
    find_test<Device> find(global_2_local, local_2_global, num_errors);
  }
  Device().fence();

  // find
  elasped_time = timer.seconds();
  std::cout << elasped_time << std::endl;

  ASSERT_EQ(num_errors, 0u);
}

}  // namespace Performance

#endif  // KOKKOS_TEST_GLOBAL_TO_LOCAL_IDS_HPP