HAi,

I wrote a cuda program , i have given the kernel function below. The device memory is
allocated through CUDAMalloc(); the value of *md is 10;

__global__ void add(int *md)

{

    int x,oper=2;
    x=threadIdx.x;

   * md = *md*oper;

if(x==1)
   {
       *md = *md*0;
   }

   if(x==2)
   {
      *md = *md*10;
   }

   if(x==3)
   {
       *md = *md+1;
   }

   if(x==4)
   {
       *md = *md-1;
   }

}

executed the above code

 add<<<1,5>>(*md) , add<<<1,4>>>(*md)

for <<<1,5>>> the output is 19

for <<<1,4>>> the output is 21

1) I have doubt that cudaMalloc() will allocate in device main memory? 2) Why the last thread alone is executed always in the above program?

Thank you