cuda-samples/Samples/vectorAddMMAP/vectorAddMMAP.cpp

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/* Vector addition: C = A + B.
 *
 * This sample replaces the device allocation in the vectorAddDrvsample with
 * cuMemMap-ed allocations.  This sample demonstrates that the cuMemMap api
 * allows the user to specify the physical properties of their memory while
 * retaining the contiguos nature of their access, thus not requiring a change
 * in their program structure.
 *
 */

// Includes
#include <cuda.h>
#include <stdio.h>
#include <string.h>
#include <cstring>
#include <iostream>

// includes, project
#include <helper_cuda_drvapi.h>
#include <helper_functions.h>

// includes, CUDA
#include <builtin_types.h>

#include "multidevicealloc_memmap.hpp"

using namespace std;

// Variables
CUdevice cuDevice;
CUcontext cuContext;
CUmodule cuModule;
CUfunction vecAdd_kernel;
float *h_A;
float *h_B;
float *h_C;
CUdeviceptr d_A;
CUdeviceptr d_B;
CUdeviceptr d_C;
size_t allocationSize = 0;

// Functions
int CleanupNoFailure();
void RandomInit(float *, int);
bool findModulePath(const char *, string &, char **, string &);

// define input ptx file for different platforms
#if defined(_WIN64) || defined(__LP64__)
#define PTX_FILE "vectorAdd_kernel64.ptx"
#else
#define PTX_FILE "vectorAdd_kernel32.ptx"
#endif

// collect all of the devices whose memory can be mapped from cuDevice.
vector<CUdevice> getBackingDevices(CUdevice cuDevice) {
  int num_devices;

  checkCudaErrors(cuDeviceGetCount(&num_devices));

  vector<CUdevice> backingDevices;
  backingDevices.push_back(cuDevice);
  for (int dev = 0; dev < num_devices; dev++) {
    int capable = 0;
    int attributeVal = 0;

    // The mapping device is already in the backingDevices vector
    if (dev == cuDevice) {
      continue;
    }

    // Only peer capable devices can map each others memory
    checkCudaErrors(cuDeviceCanAccessPeer(&capable, cuDevice, dev));
    if (!capable) {
      continue;
    }

    // The device needs to support virtual address management for the required
    // apis to work
    checkCudaErrors(cuDeviceGetAttribute(
        &attributeVal, CU_DEVICE_ATTRIBUTE_VIRTUAL_ADDRESS_MANAGEMENT_SUPPORTED,
        cuDevice));
    if (attributeVal == 0) {
      continue;
    }

    backingDevices.push_back(dev);
  }
  return backingDevices;
}

// Host code
int main(int argc, char **argv) {
  printf("Vector Addition (Driver API)\n");
  int N = 50000;
  size_t size = N * sizeof(float);
  int attributeVal = 0;

  // Initialize
  checkCudaErrors(cuInit(0));

  cuDevice = findCudaDeviceDRV(argc, (const char **)argv);

  // Check that the selected device supports virtual address management
  checkCudaErrors(cuDeviceGetAttribute(
      &attributeVal, CU_DEVICE_ATTRIBUTE_VIRTUAL_ADDRESS_MANAGEMENT_SUPPORTED,
      cuDevice));
  printf("Device %d VIRTUAL ADDRESS MANAGEMENT SUPPORTED = %d.\n", cuDevice,
         attributeVal);
  if (attributeVal == 0) {
    printf("Device %d doesn't support VIRTUAL ADDRESS MANAGEMENT.\n", cuDevice);
    exit(EXIT_WAIVED);
  }

  // The vector addition happens on cuDevice, so the allocations need to be
  // mapped there.
  vector<CUdevice> mappingDevices;
  mappingDevices.push_back(cuDevice);

  // Collect devices accessible by the mapping device (cuDevice) into the
  // backingDevices vector.
  vector<CUdevice> backingDevices = getBackingDevices(cuDevice);

  // Create context
  checkCudaErrors(cuCtxCreate(&cuContext, 0, cuDevice));

  // first search for the module path before we load the results
  string module_path, ptx_source;

  if (!findModulePath(PTX_FILE, module_path, argv, ptx_source)) {
    if (!findModulePath("vectorAdd_kernel.cubin", module_path, argv,
                        ptx_source)) {
      printf("> findModulePath could not find <vectorAdd> ptx or cubin\n");
      exit(EXIT_FAILURE);
    }
  } else {
    printf("> initCUDA loading module: <%s>\n", module_path.c_str());
  }

  // Create module from binary file (PTX or CUBIN)
  if (module_path.rfind("ptx") != string::npos) {
    // in this branch we use compilation with parameters
    const unsigned int jitNumOptions = 3;
    CUjit_option *jitOptions = new CUjit_option[jitNumOptions];
    void **jitOptVals = new void *[jitNumOptions];

    // set up size of compilation log buffer
    jitOptions[0] = CU_JIT_INFO_LOG_BUFFER_SIZE_BYTES;
    int jitLogBufferSize = 1024;
    jitOptVals[0] = (void *)(size_t)jitLogBufferSize;

    // set up pointer to the compilation log buffer
    jitOptions[1] = CU_JIT_INFO_LOG_BUFFER;
    char *jitLogBuffer = new char[jitLogBufferSize];
    jitOptVals[1] = jitLogBuffer;

    // set up pointer to set the Maximum # of registers for a particular kernel
    jitOptions[2] = CU_JIT_MAX_REGISTERS;
    int jitRegCount = 32;
    jitOptVals[2] = (void *)(size_t)jitRegCount;

    checkCudaErrors(cuModuleLoadDataEx(&cuModule, ptx_source.c_str(),
                                       jitNumOptions, jitOptions,
                                       (void **)jitOptVals));

    printf("> PTX JIT log:\n%s\n", jitLogBuffer);
  } else {
    checkCudaErrors(cuModuleLoad(&cuModule, module_path.c_str()));
  }

  // Get function handle from module
  checkCudaErrors(
      cuModuleGetFunction(&vecAdd_kernel, cuModule, "VecAdd_kernel"));

  // Allocate input vectors h_A and h_B in host memory
  h_A = (float *)malloc(size);
  h_B = (float *)malloc(size);
  h_C = (float *)malloc(size);

  // Initialize input vectors
  RandomInit(h_A, N);
  RandomInit(h_B, N);

  // Allocate vectors in device memory
  // note that a call to cuCtxEnablePeerAccess is not needed even though
  // the backing devices and mapping device are not the same.
  // This is because the cuMemSetAccess call explicitly specifies
  // the cross device mapping.
  // cuMemSetAccess is still subject to the constraints of cuDeviceCanAccessPeer
  // for cross device mappings (hence why we checked cuDeviceCanAccessPeer
  // earlier).
  checkCudaErrors(simpleMallocMultiDeviceMmap(&d_A, &allocationSize, size,
                                              backingDevices, mappingDevices));
  checkCudaErrors(simpleMallocMultiDeviceMmap(&d_B, NULL, size, backingDevices,
                                              mappingDevices));
  checkCudaErrors(simpleMallocMultiDeviceMmap(&d_C, NULL, size, backingDevices,
                                              mappingDevices));

  // Copy vectors from host memory to device memory
  checkCudaErrors(cuMemcpyHtoD(d_A, h_A, size));
  checkCudaErrors(cuMemcpyHtoD(d_B, h_B, size));

  // This is the new CUDA 4.0 API for Kernel Parameter Passing and Kernel Launch
  // (simpler method)

  // Grid/Block configuration
  int threadsPerBlock = 256;
  int blocksPerGrid = (N + threadsPerBlock - 1) / threadsPerBlock;

  void *args[] = {&d_A, &d_B, &d_C, &N};

  // Launch the CUDA kernel
  checkCudaErrors(cuLaunchKernel(vecAdd_kernel, blocksPerGrid, 1, 1,
                                 threadsPerBlock, 1, 1, 0, NULL, args, NULL));

  // Copy result from device memory to host memory
  // h_C contains the result in host memory
  checkCudaErrors(cuMemcpyDtoH(h_C, d_C, size));

  // Verify result
  int i;

  for (i = 0; i < N; ++i) {
    float sum = h_A[i] + h_B[i];

    if (fabs(h_C[i] - sum) > 1e-7f) {
      break;
    }
  }

  CleanupNoFailure();
  printf("%s\n", (i == N) ? "Result = PASS" : "Result = FAIL");

  exit((i == N) ? EXIT_SUCCESS : EXIT_FAILURE);
}

int CleanupNoFailure() {
  // Free device memory
  checkCudaErrors(simpleFreeMultiDeviceMmap(d_A, allocationSize));
  checkCudaErrors(simpleFreeMultiDeviceMmap(d_B, allocationSize));
  checkCudaErrors(simpleFreeMultiDeviceMmap(d_C, allocationSize));

  // Free host memory
  if (h_A) {
    free(h_A);
  }

  if (h_B) {
    free(h_B);
  }

  if (h_C) {
    free(h_C);
  }

  checkCudaErrors(cuCtxDestroy(cuContext));

  return EXIT_SUCCESS;
}
// Allocates an array with random float entries.
void RandomInit(float *data, int n) {
  for (int i = 0; i < n; ++i) {
    data[i] = rand() / (float)RAND_MAX;
  }
}

bool inline findModulePath(const char *module_file, string &module_path,
                           char **argv, string &ptx_source) {
  char *actual_path = sdkFindFilePath(module_file, argv[0]);

  if (actual_path) {
    module_path = actual_path;
  } else {
    printf("> findModulePath file not found: <%s> \n", module_file);
    return false;
  }

  if (module_path.empty()) {
    printf("> findModulePath could not find file: <%s> \n", module_file);
    return false;
  } else {
    printf("> findModulePath found file at <%s>\n", module_path.c_str());

    if (module_path.rfind(".ptx") != string::npos) {
      FILE *fp = fopen(module_path.c_str(), "rb");
      fseek(fp, 0, SEEK_END);
      int file_size = ftell(fp);
      char *buf = new char[file_size + 1];
      fseek(fp, 0, SEEK_SET);
      fread(buf, sizeof(char), file_size, fp);
      fclose(fp);
      buf[file_size] = '\0';
      ptx_source = buf;
      delete[] buf;
    }

    return true;
  }
}