printing from cuda kernels
I am writing a cuda program and trying to print something inside the cuda kernels using the printf function. But when I am compiling the program then I am getting an error
error : calling a host function("printf") from a __device__/__global__ function("agent_movement_top") is not allowed
error MSB3721: The command ""C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.2\bin\nvcc.exe" -gencode=arch=compute_10,code=\"sm_10,compute_10\" --use-local-env --cl-version 2008 -ccbin "c:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\bin" -I"C:\ProgramData\NVIDIA Corporation\NVIDIA GPU Computing SDK 4.2\C\common\inc" -I"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v4.2\include" -G --keep-dir "Debug" -maxrregcount=0 --machine 32 --compile -g -Xcompiler "/EHsc /nologo /Od /Zi /MDd " -o "Debug\test.cu.obj" "C:\Users\umdutta\Desktop\SANKHA_ALL_MATERIALS\PROGRAMMING_FOLDER\ABM_MODELLING_2D_3D\TRY_NUM_2\test_proj_test\test_proj\test_proj\test.cu"" exited with code 2.
I am using the card GTX 560 ti having a compute capability greater than 2.0 and when I have searched a bit about the printing from cuda kernels I also saw that I need to change the compiler from sm_10 to sm_2.0 to take the full advantage of the card. Also some suggested for cuPrintf to serve the purpose. I am bit confused what should I do and what should be the simplest and quickest way to get the printouts on my console screen. If I need to change the nvcc compiler from 1.0 to 2.0 then what should I do? One more thing I would like to mention that I am using windows 7.0 and programming in visual studio 2010. Thanks for all your help.
Answer
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.