英文:
Golang calling CUDA library
问题
我正在尝试从我的Go代码中调用一个CUDA函数。
我有以下三个文件。
test.h:
int test_add(void);
test.cu:
__global__ void add(int *a, int *b, int *c){*c = *a + *b;}int test_add(void) {int a, b, c; // a、b、c的主机副本int *d_a, *d_b, *d_c; // a、b、c的设备副本int size = sizeof(int);// 为a、b、c的设备副本分配空间cudaMalloc((void **)&d_a, size);cudaMalloc((void **)&d_b, size);cudaMalloc((void **)&d_c, size);// 设置输入值a = 2;b = 7;// 将输入复制到设备cudaMemcpy(d_a, &a, size, cudaMemcpyHostToDevice);cudaMemcpy(d_b, &b, size, cudaMemcpyHostToDevice);// 在GPU上启动add()内核add<<<1,1>>>(d_a, d_b, d_c);// 将结果复制回主机cudaMemcpy(&c, d_c, size, cudaMemcpyDeviceToHost);// 清理cudaFree(d_a); cudaFree(d_b); cudaFree(d_c);return 0;}
test.go:
package mainimport "fmt"//#cgo CFLAGS: -I.//#cgo LDFLAGS: -L. -ltest//#cgo LDFLAGS: -lcudart//#include <test.h>import "C"func main() {fmt.Printf("调用cuda库...\n")fmt.Println("完成 ", C.test_add())}
我使用以下命令编译CUDA代码：
nvcc -m64 -arch=sm_20 -o libtest.so --shared -Xcompiler -fPIC test.cu
test.h、test.cu和test.go这三个文件都在同一个目录中。
当我尝试使用go构建时，我得到的错误是"undefined reference to `test_add'"。
我对C/C++几乎没有经验，对CUDA完全是个新手。
我已经尝试解决这个问题两天了，非常感谢任何帮助。
谢谢。
英文:
I am trying to call a CUDA function from my Go code.
I have the following three files.
test.h:
int test_add(void);
test.cu:
__global__ void add(int *a, int *b, int *c){*c = *a + *b;}int test_add(void) {int a, b, c; // host copies of a, b, cint *d_a, *d_b, *d_c; // device copies of a, b, cint size = sizeof(int);// Allocate space for device copies of a, b, ccudaMalloc((void **)&d_a, size);cudaMalloc((void **)&d_b, size);cudaMalloc((void **)&d_c, size);// Setup input valuesa = 2;b = 7;// Copy inputs to devicecudaMemcpy(d_a, &a, size, cudaMemcpyHostToDevice);cudaMemcpy(d_b, &b, size, cudaMemcpyHostToDevice);// Launch add() kernel on GPUadd<<<1,1>>>(d_a, d_b, d_c);// Copy result back to hostcudaMemcpy(&c, d_c, size, cudaMemcpyDeviceToHost);// CleanupcudaFree(d_a); cudaFree(d_b); cudaFree(d_c);return 0;}
test.go:
package mainimport "fmt"//#cgo CFLAGS: -I.//#cgo LDFLAGS: -L. -ltest//#cgo LDFLAGS: -lcudart//#include <test.h>import "C"func main() {fmt.Printf("Invoking cuda library...\n")fmt.Println("Done ", C.test_add())}
I am compiling CUDA code with:
nvcc -m64 -arch=sm_20 -o libtest.so --shared -Xcompiler -fPIC test.cu
All three files - test.h, test.cu and test.go are in the same directory.
The error I am getting when I try to build with go is "undefined reference to `test_add'".
I have very little experience with C/C++ and am a total novice in CUDA.
I've been trying to solve my problem for two days now and would be
very grateful for any input.
Thanks.
答案1
得分: 5
在这种情况下，似乎go导入C时期望函数提供C风格链接。
CUDA（即nvcc）主要遵循C++模式，并默认提供C++风格的链接（包括函数名重载等）。
可以使用extern "C" {...code...}强制将代码段提供给外部，而不是使用C++风格的链接。这是C++语言的特性，与CUDA或nvcc无关。
因此，通过对test.cu进行以下修改，可以解决该问题：
extern "C" { int test_add(void) { ... code ... }; }
英文:
It appears, at least in this case, that the go import of C is expecting the function to be provided with C style linkage.
CUDA (i.e. nvcc) mainly follows C++ patterns and provides by default C++ style linkage (including function name mangling, etc.)
It's possible to force a section of code to be provided externally using C rather than C++ style linkage using extern "C" {...code...}. This is a C++ language feature and not specific to CUDA or nvcc.
Therefore it appears the problem can be solved via the following modification to the test.cu:
extern "C" { int test_add(void) { ... code ... }; }
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