c++ - OpenCL——不同设备上的不同内核 "printf()"结果？

Question

运行 hello_world 内核后，我得到了一个奇怪的结果，该内核仅打印通过命令队列传递的缓冲区。我从同一平台上的不同设备得到两个不同的结果。请参阅下面的控制台输出底部:

这是我的内核代码:

__kernel void hello_world (__global char* message, int messageSize) {
    for (int i =0; i < messageSize; i++) {
        printf("%c", message[i]);
    }
}

这是我的函数调用:

  std::string message = "Hello World!";
  int messageSize = message.length();
  std::cout << "          ---> Creating Buffer... ";
  cl::Buffer buffer(CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR, sizeof(char) * messageSize, (char*)message.c_str());

  kernel.setArg(0,buffer);
  kernel.setArg(1,sizeof(int),&messageSize);
  std::cout << "Done!" << std::endl;

  for (cl_uint i = 0; i<m_deviceCount[m_currentPlatform]; i++) {
        std::cout << "          ---> Queuing Kernel Task on Device #"<< m_currentPlatform << "." << i << "... ";
        m_commandQueues[i].enqueueTask(kernel);
        std::cout << "Done!" << std::endl;
        std::cout << "          ---> Executing... Output:\n\n";
        m_commandQueues[i].finish();
        std::cout << "\n\n          ---> Done!" << std::endl;
    }

我的控制台输出:

Found 1 Platforms

Platform #0:
  Name:  AMD Accelerated Parallel Processing
  Found  2 Devices
      Device #0.0:
          --> Name:               Juniper
          --> Vendor:             Advanced Micro Devices, Inc.
          --> Max Compute Units:  10
          --> Max Clock Freq:     850
          --> Global Mem Size:    512 MBs
          --> Local Mem Size:     32 KBs
          --> Hardware Version:   OpenCL 1.2 AMD-APP (1800.11)
          --> Software Version:   1800.11
          --> Open CL Version:    OpenCL C 1.2 
          --> Images Supported:   YES
      Device #0.1:
          --> Name:               Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
          --> Vendor:             GenuineIntel
          --> Max Compute Units:  8
          --> Max Clock Freq:     3796
          --> Global Mem Size:    15905 MBs
          --> Local Mem Size:     32 KBs
          --> Hardware Version:   OpenCL 1.2 AMD-APP (1800.11)
          --> Software Version:   1800.11 (sse2,avx)
          --> Open CL Version:    OpenCL C 1.2 
          --> Images Supported:   YES

    Using Platform With Most Available Devices: Platform #0
          ---> Creating Context.... Done!
          ---> Creating Command Queue for Device #0.0.... Done!
          ---> Creating Command Queue for Device #0.1.... Done!
          ---> Loading Program: hello_world.cl...
                  > Compiling... Done!
          ---> Creating Buffer... Done!

          ---> Queuing Kernel Task on Device #0.0... Done!
          ---> Executing... Output:

H(null)e(null)l(null)l(null)o(null) (null)W(null)o(null)r(null)l(null)d(null)!(null)

          ---> Done!
          ---> Queuing Kernel Task on Device #0.1... Done!
          ---> Executing... Output:

Hello World!

          ---> Done!

有谁知道为什么 AMD GPU 在字符之间插入“(null)”，而 Intel CPU 则不然？这对于 AMD 的 OpenCL 实现来说是正常的吗？

Answer 1

我还尝试在内核中实现 printf 。您可以引用我的程序:

https://github.com/pradyotsn/opencl_printf

谢谢