Hey everyone,
I am starting an undergraduate project with some peers currently using Linux and CUDA to study parallel processing using a GPU. That being said, I can’t get the darn thing to work.
I tried running a basic hello world program and came up with some problems. This program has been tested, and I have tried other code and come to similar results.
[codebox]/*
** Hello World using CUDA
**
** The string “Hello World!” is mangled then restored using a common CUDA idiom
**
** Byron Galbraith
** 2009-02-18
*/
#include <cuda.h>
#include <stdio.h>
// Prototypes
global void helloWorld(char*);
// Host function
int
main(int argc, char** argv)
{
int i;
// desired output
char str = “Hello World!”;
// mangle contents of output
// the null character is left intact for simplicity
for(i = 0; i < 12; i++)
str[i] -= i;
// allocate memory on the device
char *d_str;
size_t size = sizeof(str);
cudaMalloc((void**)&d_str, size);
// copy the string to the device
cudaMemcpy(d_str, str, size, cudaMemcpyHostToDevice);
// set the grid and block sizes
dim3 dimGrid(2); // one block per word
dim3 dimBlock(6); // one thread per character
// invoke the kernel
helloWorld<<< dimGrid, dimBlock >>>(d_str);
// retrieve the results from the device
cudaMemcpy(str, d_str, size, cudaMemcpyDeviceToHost);
// free up the allocated memory on the device
cudaFree(d_str);
// everyone’s favorite part
printf(“%s\n”, str);
return 0;
}
// Device kernel
global void
helloWorld(char* str)
{
// determine where in the thread grid we are
int idx = blockIdx.x * blockDim.x + threadIdx.x;
// unmangle output
str[idx] += idx;
}[/codebox]
It compiles just fine, but when I run it, it returns HdjikeQhjcZ
This indicates to me that the GPU is not being accessed correctly. Any advice on the situation would be greatly appreciated.
Thanks!