使用所有CPU和GPU设备创建OpenCL上下文

Question

我使用的是OpenCL 1.1。我将在我所有的gpu和cpu上运行我的代码。因此，由于很难在两个不同的上下文上进行同步，我想创建一个包含所有CPU和GPU作为设备的上下文。所以，首先我要得到所有的平台，然后是与每个平台相关的设备，然后得到CPU&GPU设备，并将它们存储在单独的矢量中。然后，为了制作上下文，我将创建一个由所有CPU和GPU设备制作的向量。然后，我将呼叫clCreateContext。它会很好地工作，但之后，当我想为每个设备分别创建命令队列时，它总是给我：

OpenCL call falls with error -34.

代码如下：

  cl_int error = CL_SUCCESS;
  cl_uint num_platforms;
  clGetPlatformIDs(0, nullptr, &num_platforms);
  if (num_platforms == 0){
    std::cout << "Cannot find any platform.n";
    return;
  }
  platform.resize(num_platforms);
  error = clGetPlatformIDs(num_platforms, platform.data(), nullptr);
  checkError(error);
  for (cl_uint i = 0; i < num_platforms; i++){
    std::string platform_name;
    size_t platform_name_len;
    clGetPlatformInfo(platform[i], CL_PLATFORM_NAME, 0, nullptr, &platform_name_len);
    platform_name.resize(platform_name_len);
    clGetPlatformInfo(platform[i], CL_PLATFORM_NAME, platform_name_len, const_cast<char*>(platform_name.data()), nullptr);
    std::cout << "[" << i << "]t" << platform_name << std::endl;
    std::vector<cl_device_id> devices(0);
    cl_uint num_cpus = 0, num_gpus = 0;
    error = clGetDeviceIDs(platform[i], CL_DEVICE_TYPE_CPU, 0, nullptr, &num_cpus);
    error = clGetDeviceIDs(platform[i], CL_DEVICE_TYPE_GPU, 0, nullptr, &num_gpus);
    devices.resize(num_cpus);
    std::cout << "tCPUS: n";
    error = clGetDeviceIDs(platform[i], CL_DEVICE_TYPE_CPU, num_cpus, devices.data(), nullptr);
    for (cl_uint d = 0; d < num_cpus; d++){
      std::string device_name;
      size_t device_name_len;
      clGetDeviceInfo(devices[d], CL_DEVICE_NAME, 0, nullptr, &device_name_len);
      device_name.resize(device_name_len);
      clGetDeviceInfo(devices[d], CL_DEVICE_NAME, device_name_len, const_cast<char*>(device_name.data()), nullptr);
      std::cout << "tt[" << d << "]t" << device_name << std::endl;
      cpu_devices.push_back(devices[d]);
    }
    std::cout << "tGPUS: n";
    devices.resize(num_gpus);
    error = clGetDeviceIDs(platform[i], CL_DEVICE_TYPE_GPU, num_gpus, devices.data(), nullptr);
    for (cl_uint d = 0; d < num_gpus; d++){
      std::string device_name;
      size_t device_name_len;
      clGetDeviceInfo(devices[d], CL_DEVICE_NAME, 0, nullptr, &device_name_len);
      device_name.resize(device_name_len);
      clGetDeviceInfo(devices[d], CL_DEVICE_NAME, device_name_len, const_cast<char*>(device_name.data()), nullptr);
      std::cout << "tt[" << d << "]t" << device_name << std::endl;
      gpu_devices.push_back(devices[d]);
    }
  }
  std::vector<cl_device_id> devices;
  for (size_t i = 0; i < cpu_devices.size(); i++)
    devices.push_back(cpu_devices[i]);
  for (size_t i = 0; i < gpu_devices.size(); i++)
    devices.push_back(gpu_devices[i]);
  ctx = clCreateContext(NULL, static_cast<cl_uint>(devices.size()), devices.data(), nullptr, nullptr, nullptr);
  cpu_devices_queue.resize(cpu_devices.size());
  for (size_t i = 0; i < cpu_devices.size(); i++){
    cpu_devices_queue[i] = clCreateCommandQueue(ctx, cpu_devices[i], 0, &error);
    checkError(error);
  }
  gpu_devices_queue.resize(gpu_devices.size());
  for (size_t i = 0; i < gpu_devices.size(); i++){
    gpu_devices_queue[i] = clCreateCommandQueue(ctx, gpu_devices[i], 0, &error);
    checkError(error);
  }

Answer 1

OpenCL上下文只能封装来自单个平台的设备，不能使用来自两个或多个不同平台的设备创建。

实际上，您并没有检查对clCreateContext的调用是否成功。如果您检查了返回值或错误代码，您可能会发现它实际上失败了。这就是为什么当您稍后在对clCreateCommandQueue的调用中使用该上下文时，会收到错误-34（CL_INVALID_CONTEXT）。