Question

I have Nvidia geforce 310M and when i write this code

int main()
{
    int dev;
    cudaDeviceProp prop;
    cudaGetDevice(&dev);
    cudaGetDeviceProperties(&prop,dev);
    cout << "Device name " << prop.name << endl;
    cout << "warp size  = " << prop.warpSize << endl;
    cout << "mutiprocesosrs = " << prop.multiProcessorCount << endl;
    return 0;
}

it writes :

Device name ♀
warp size  = -2144521342
mutiprocesosrs = 0
Press any key to continue . . .

and every time i run this program it produces different warp size.
how can i fix that ?

(p.s. I’m using visual studio 2010)

Answer 1

Check first of all whether the function calls succeed!

cudaDeviceProp prop;
int dev;

if (cudaGetDevice(&dev) != cudaSuccess)
{
  /* error */
  abort();
}

if (cudaGetDeviceProperties(&prop, dev) != cudaSuccess)
{
  /* error */
  abort();
}

---

I made a little macro I use for calling all CUDA functions which takes care of the checking and throws a custom exception:

#define CUDACALL(F, ARGS...) do { e = F(ARGS); if (e != cudaSuccess) throw cudaException(#F, e); } while (false)

With this, I just say,

try
{
   int dev;
   cudaDeviceProp prop;
   CUDACALL(cudaGetDevice, &dev);
   CUDACALL(cudaGetDeviceProperties, &prop, dev);
   // ...
}
catch (cudeException const & e)
{
  std::cerr << "Cuda error: " << e.what() << "\n";
}

The exception class is defined as follows:

struct cudaException : public std::exception
{
  cudaException(const std::string & str, cudaError_t err) : s(str), e(err) { }

  ~cudaException() throw() { }

  virtual const char * what() const throw()
  {
    const std::string r = s + ": \"" + cudaGetErrorString(e) + "\" (" + (char)(e + '0') + ')';
    return r.c_str();
  }
private:
  std::string s;
  cudaError_t e;
};