Use of Cuda Thrust device_vector crashes [closed]

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Below I've posted some code that I'm using to try and get a feel for the CUDA thrust library. Before anyone says anything I know this is an extremely inefficient way to find prime numbers, I just want something to test parallelism. Unfortunatly when I run this I get an error here is what pops up: Unhandled exception at at 0x76FCC41F in Thrust_2.exe: Microsoft C++ exception: thrust::system::system_error at memory location 0x0022F500.

If I switch the device_vector to a host_vector in the doTest function I no longer get the error and the program works flawlessly. Why does this happen and how can I get it to use the device_vector without crashing? I would like to do as much in parallel is possible. Also the entire program works as intended with a host_vector.

PS:

I'm using VS2012

Cuda: V5.5

GPU: geforce gt 540M

Thrust: Got with cuda.

Thanks in advance!

  struct prime{
__host__ __device__
    void operator()(long& x){
    bool result = true;
    long stop = ceil(sqrt((float)x));
    if(x%2!=0){
        for(int i = 3;i<stop;i+=2){
            if(x%i==0){
                result = false;
                break;
            };
        }
    }else{
        result = false;
    }
    if(!result)
        x = -1;
 }
};
void doTest(long gen){
  using namespace thrust;
  device_vector<long> tNum(gen);
  sequence(tNum.begin(),tNum.end()); // fails here when using a device_vector
}
int main(){
   doTest(1000);
   return 0;
}

Answer 1

The issue was i had the wrong compiler arguments, I feel really stupid now...

i was compiling for 1.0, I switched it to 2.0 and now its working.

Answer 2

This is a problem:

void operator()(long& x){
bool result = true;
long stop = ceil(sqrt(x));

And in fact you should be receiving a warning message from the compiler about it.

The sqrt function available in device code is only available for float and double arguments. Your argument is of type long. This means the compiler will attempt to use a host-library version of the sqrt function, which will not work in device code. When you create your vector as a host vector, this is not a problem, as the functor is being run in host code. However when you switch to a device vector, the functor (running on the device) will crash at that point, and throw a thrust error.

As a simple test, you could modify it to:

long stop = ceil(sqrt((float)x));

and see if it eliminates the crash. Whether or not the cast from long to float is valid for your code is something you will have to decide.