cuda-samples/Samples/radixSortThrust/radixSortThrust.cu

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#include <thrust/host_vector.h>
#include <thrust/device_vector.h>
#include <thrust/sort.h>
#include <thrust/copy.h>
#include <thrust/sequence.h>
#include <thrust/random.h>
#include <thrust/generate.h>
#include <thrust/detail/type_traits.h>

#include <helper_cuda.h>

#include <algorithm>
#include <time.h>
#include <limits.h>

template <typename T, bool floatKeys>
bool testSort(int argc, char **argv) {
  int cmdVal;
  int keybits = 32;

  unsigned int numElements = 1048576;
  bool keysOnly = checkCmdLineFlag(argc, (const char **)argv, "keysonly");
  bool quiet = checkCmdLineFlag(argc, (const char **)argv, "quiet");

  if (checkCmdLineFlag(argc, (const char **)argv, "n")) {
    cmdVal = getCmdLineArgumentInt(argc, (const char **)argv, "n");
    numElements = cmdVal;

    if (cmdVal < 0) {
      printf("Error: elements must be > 0, elements=%d is invalid\n", cmdVal);
      exit(EXIT_SUCCESS);
    }
  }

  if (checkCmdLineFlag(argc, (const char **)argv, "keybits")) {
    cmdVal = getCmdLineArgumentInt(argc, (const char **)argv, "keybits");
    keybits = cmdVal;

    if (keybits <= 0) {
      printf("Error: keybits must be > 0, keybits=%d is invalid\n", keybits);
      exit(EXIT_SUCCESS);
    }
  }

  unsigned int numIterations = (numElements >= 16777216) ? 10 : 100;

  if (checkCmdLineFlag(argc, (const char **)argv, "iterations")) {
    cmdVal = getCmdLineArgumentInt(argc, (const char **)argv, "iterations");
    numIterations = cmdVal;
  }

  if (checkCmdLineFlag(argc, (const char **)argv, "help")) {
    printf("Command line:\nradixSortThrust [-option]\n");
    printf("Valid options:\n");
    printf("-n=<N>        : number of elements to sort\n");
    printf("-keybits=bits : keybits must be > 0\n");
    printf(
        "-keysonly     : only sort an array of keys (default sorts key-value "
        "pairs)\n");
    printf(
        "-float        : use 32-bit float keys (default is 32-bit unsigned "
        "int)\n");
    printf(
        "-quiet        : Output only the number of elements and the time to "
        "sort\n");
    printf("-help         : Output a help message\n");
    exit(EXIT_SUCCESS);
  }

  if (!quiet)
    printf("\nSorting %d %d-bit %s keys %s\n\n", numElements, keybits,
           floatKeys ? "float" : "unsigned int",
           keysOnly ? "(only)" : "and values");

  int deviceID = -1;

  if (cudaSuccess == cudaGetDevice(&deviceID)) {
    cudaDeviceProp devprop;
    cudaGetDeviceProperties(&devprop, deviceID);
    unsigned int totalMem = (keysOnly ? 2 : 4) * numElements * sizeof(T);

    if (devprop.totalGlobalMem < totalMem) {
      printf("Error: insufficient amount of memory to sort %d elements.\n",
             numElements);
      printf("%d bytes needed, %d bytes available\n", (int)totalMem,
             (int)devprop.totalGlobalMem);
      exit(EXIT_SUCCESS);
    }
  }

  thrust::host_vector<T> h_keys(numElements);
  thrust::host_vector<T> h_keysSorted(numElements);
  thrust::host_vector<unsigned int> h_values;

  if (!keysOnly) h_values = thrust::host_vector<unsigned int>(numElements);

  // Fill up with some random data
  thrust::default_random_engine rng(clock());

  if (floatKeys) {
    thrust::uniform_real_distribution<float> u01(0, 1);

    for (int i = 0; i < (int)numElements; i++) h_keys[i] = u01(rng);
  } else {
    thrust::uniform_int_distribution<unsigned int> u(0, UINT_MAX);

    for (int i = 0; i < (int)numElements; i++) h_keys[i] = u(rng);
  }

  if (!keysOnly) thrust::sequence(h_values.begin(), h_values.end());

  // Copy data onto the GPU
  thrust::device_vector<T> d_keys;
  thrust::device_vector<unsigned int> d_values;

  // run multiple iterations to compute an average sort time
  cudaEvent_t start_event, stop_event;
  checkCudaErrors(cudaEventCreate(&start_event));
  checkCudaErrors(cudaEventCreate(&stop_event));

  float totalTime = 0;

  for (unsigned int i = 0; i < numIterations; i++) {
    // reset data before sort
    d_keys = h_keys;

    if (!keysOnly) d_values = h_values;

    checkCudaErrors(cudaEventRecord(start_event, 0));

    if (keysOnly)
      thrust::sort(d_keys.begin(), d_keys.end());
    else
      thrust::sort_by_key(d_keys.begin(), d_keys.end(), d_values.begin());

    checkCudaErrors(cudaEventRecord(stop_event, 0));
    checkCudaErrors(cudaEventSynchronize(stop_event));

    float time = 0;
    checkCudaErrors(cudaEventElapsedTime(&time, start_event, stop_event));
    totalTime += time;
  }

  totalTime /= (1.0e3f * numIterations);
  printf(
      "radixSortThrust, Throughput = %.4f MElements/s, Time = %.5f s, Size = "
      "%u elements\n",
      1.0e-6f * numElements / totalTime, totalTime, numElements);

  getLastCudaError("after radixsort");

  // Get results back to host for correctness checking
  thrust::copy(d_keys.begin(), d_keys.end(), h_keysSorted.begin());

  if (!keysOnly)
    thrust::copy(d_values.begin(), d_values.end(), h_values.begin());

  getLastCudaError("copying results to host memory");

  // Check results
  bool bTestResult =
      thrust::is_sorted(h_keysSorted.begin(), h_keysSorted.end());

  checkCudaErrors(cudaEventDestroy(start_event));
  checkCudaErrors(cudaEventDestroy(stop_event));

  if (!bTestResult && !quiet) {
    return false;
  }

  return bTestResult;
}

int main(int argc, char **argv) {
  // Start logs
  printf("%s Starting...\n\n", argv[0]);

  findCudaDevice(argc, (const char **)argv);

  bool bTestResult = false;

  if (checkCmdLineFlag(argc, (const char **)argv, "float"))
    bTestResult = testSort<float, true>(argc, argv);
  else
    bTestResult = testSort<unsigned int, false>(argc, argv);

  printf(bTestResult ? "Test passed\n" : "Test failed!\n");
}