How do we use cuPrintf()?

Question

What do we have to do to use cuPrintf()? (device compute capability 1.2, Ubuntu 12) I couldn't find "cuPrintf.cu" and "cudaPrintf.cuh", so i downloaded their code and include them:

#include "cuPrintf.cuh"
#include "cuPrintf.cu"

By the way this is the rest of the code:

__global__ void hello_kernel (float f) {
printf ("Thread number %d. f = %d\n", threadIdx.x, f);
}

    int main () {
    dim3 gridSize = dim3 (1);
    dim3 blockSize = dim3 (16);
    cudaPrintfInit ();
    hello_kernel <<< gridSize, blockSize >>> (1.2345f);
    cudaPrintfDisplay (stdout, true);
    cudaPrintfEnd ();
    return (0);
}

But nvcc still gives a mistake:

max@max-Lenovo-G560:~/CUDA/matrixMult$ nvcc printfTest.cu -o printfTest

printfTest.cu(5): error: calling a __host__ function("printf") from a __global__
function("hello_kernel") is not allowed

Thanks!

call `cuPrintf` in your kernel not `printf` – talonmies Nov 28 '12 at 15:31 — talonmies, Nov 28 '12 at 15:31

score 3 · Accepted Answer · edited May 23 '17 at 12:12

3

In your kernel instead of this:

printf ("Thread number %d. f = %d\n", threadIdx.x, f);

you should do this:

cuPrintf ("Thread number %d. f = %d\n", threadIdx.x, f);

Other than that, I believe your code is correct (it works for me).

This SO question/answer gives more tips about using cuPrintf properly.

edited May 23 '17 at 12:12

Community

1
1

answered Nov 28 '12 at 15:34

Robert Crovella

143,785
11
213
257

Oops! First I tried to use printf(), but then found out that compute capability is lower than 2.0. Finally I forgot to change printf() to cuPrintf(). Sorry for stupid question :( – Max Nov 28 '12 at 16:35

score -1 · Answer 2 · answered Nov 28 '12 at 15:37

-1

Include <stdio.h> and compile with -arch=sm_20.

Details:

code:

#include <stdio.h>
__global__ void hello_kernel (float f) {
    printf ("Thread number %d. f = %d\n", threadIdx.x, f);
}

int main(){
    return 0;
}

compilations:

 nvcc -arch=sm_20 -o printfTest printfTest.cu

answered Nov 28 '12 at 15:37

lashgar

5,184
3
37
45

That is kernel printf, not cuPrintf – talonmies Nov 28 '12 at 16:24
Oops! I missed the compute capability. – lashgar Nov 28 '12 at 17:54

How do we use cuPrintf()?

2 Answers2

Linked

Related