not able to use printf in cuda kernel function
cuda, printf
Solution
Quoting the CUDA Programming Guide "Formatted output is only supported by devices of compute capability 2.x and higher". See the programming guide for additional information.
Devices of compute capability < 2.x can use cuPrintf.
If you are on a 2.x and above device and you are trying to use printf make sure you have specified arch=sm_20 (or higher). The default is sm_10 which does not have sufficient features to support printf.
NVIDIA offers three source level debuggers for CUDA. You may find these more useful than printf for inspecting variables. - Nsight Visual Studio Edition CUDA Debugger - Nsight Eclipse Edition CUDA Debugger - cuda-gdb
Problem
It seems that `printf` doesn't work inside the Kernel of a cuda code ``` #include "Common.h" #include<cuda.h> #include <stdio.h> __device__ __global__ void Kernel(float *a_d , float *b_d ,int size) { int idx = threadIdx.x ; int idy = threadIdx.y ; //Allocating memory in the share memory of the device __shared__ float temp[16][16]; //Copying the data to the shared memory temp[idy][idx] = a_d[(idy * (size+1)) + idx] ; printf("idx=%d, idy=%d, size=%d\n", idx, idy, size); for(int i =1 ; i<size ;i++) { if((idy + i) < size) { // NO Thread divergence here float var1 =(-1)*( temp[i-1][i-1]/temp[i+idy][i-1]); temp[i+idy][idx] = temp[i-1][idx] +((var1) * (temp[i+idy ][idx])); } __syncthreads(); //Synchronizing all threads before Next iterat ion } b_d[idy*(size+1) + idx] = temp[idy][idx]; } ``` when compiling, it says: ``` error: calling a host function("printf") from a __device__/__global__ function("Kernel") is not allowed ``` The cuda version is 4