Where did my cuda printf output go?

Accelerated Computing CUDA CUDA Programming and Performance
1

I put a printf statement into my cuda kernel.

It output way too much stuff for my console window. So I used freopen to map stdout to a file.

But now, the console window does NOT have the cuda printf output; neither does the file I redirected stdout to (it has other stuff from my app)

Where did the cuda printf output go?

2

Why don’t you use terminal redirection instead of freopen? It is much simpler, more flexible and probably works better:

MyProgram > output.txt
3

Squisher: thanks for the reply but way too cryptic for me to understand. where? how? I am running VS2010 under Win 7. cant find “terminal redirection” anywhere. can you give more detailed response ?

4

Has anybody resolved this? Squisher’s answer is fine, but I would like more control than that – for example, I would like different kernels to output to different files. Like jm@imagemining.net, I am using VS2010, Win7, and my printf output goes into the ether when using freopen.

__global__ void printfTst()
{
	printf("This is the Kernel Output");
}

void main()
{
	cudaSetDevice(0);
	printf ("CPU output before redirection.");
	printfTst<<<1,1>>>();
	cudaDeviceSynchronize();
	freopen ("d:myfileStdOut.txt","w",stdout);
	freopen ("d:myfileStdErr.txt","w",stderr);
	printf ("CPU output redirected to a file stdout.");
	printfTst<<<1,1>>>();
	cudaDeviceSynchronize();
	cudaDeviceReset();
	fclose (stdout);
	fclose(stderr);
}