printing from cuda kernels

To enable use of plain printf() on devices of Compute Capability >= 2.0, it's important to compile for CC of at least CC 2.0 and disable the default, which includes a build for CC 1.0.

Right-click the .cu file in your project, select Properties, select Configuration Properties | CUDA C/C++ | Device. Click on the Code Generation line, click the triangle, select Edit. In the Code Generation dialog box, uncheck Inherit from parent or project defaults, type compute_20,sm_20 in the top window, click OK.

I am using GTX 1650 also GTX1050, and c++11. For recent users, this is my suggestion:

In host function:

#include<iostream>
using namespace std;

cout<< .....(anything you want) << endl;

In kernel:

if(threadIdx.x==0){
    printf("ss=%4.2f \n", ss);
}

Note that this "if" is quite important and I notice nobody mentioned this. Because you might use a lot of threads and you definitely do not want to print too much from every threads. Also 4.2f means 4 points and 2 for decimal. This can prevent print too much 00000. Also do not forget \n to jump line.

Also you can consider this to print shared memory value:

if(threadIdx.x==0){
    for(int i=0;i<64;i++){
        for(int j=0;j<8; j++){
            printf("%4.2f  ", ashare[i*8+j]);
        }
        printf("\n");
    }
    printf("\n");
}

This can print shared memory beautifully. Notice also need to restrict only in threadIdx.x==0

you can write this code to print whatever you want from inside the CUDA Kernel:

# if __CUDA_ARCH__>=200
    printf("%d \n", tid);

#endif  

and include < stdio.h >

One way of solving this problem is by using cuPrintf function which is capable of printing from the kernels. Copy the files cuPrintf.cu and cuPrintf.cuh from the folder

C:\ProgramData\NVIDIA Corporation\NVIDIA GPU Computing SDK 4.2\C\src\simplePrintf

to the project folder. Then add the header file cuPrintf.cuh to your project and add

#include "cuPrintf.cu"

to your code. Then your code should be written in a format mentioned below :

#include "cuPrintf.cu"
__global__ void testKernel(int val)
{
  cuPrintf("Value is: %d\n", val);
}

int main()
{
  cudaPrintfInit();
  testKernel<<< 2, 3 >>>(10);
  cudaPrintfDisplay(stdout, true);
  cudaPrintfEnd();
  return 0;
}

By following the above procedure one can get a print on the console window from the device function. Though I solved my issues in the above mentioned way I still don't have the solution of using printf from the device function. If it is true and absolutely necessary to upgrade my nvcc compiler from sm_10 to sm_21 to enable the printf feature then it would be very much helpful if someone could show me the light. Thanks for all your cooperation