我正在尝试释放dev_inp我在CUDA + OpenGL互操作代码中分配的设备内存.检查错误后,我收到Invalid Device Pointer错误,程序在cudaFree(dev_inp);我的renderScene()函数结束时停止执行.一切都很好,但我担心内存泄漏.
问题:
一个.为什么我无法释放我分配的本地设备内存？我cuda_resource从像素缓冲区对象中取消映射,并取消注册资源.
从CUDA C编程指南的B.17节:
Memory allocated via malloc() cannot be freed using the runtime (i.e. by calling any of the free memory functions from Sections 3.2.2).
所以,这引出了另外两个问题:
湾 我没有malloc在内核中编写内存,因为我没有内存.那么,利用这个cudaFree功能应该(技术上？)在这里工作吗？是由程序员解除提供给本地定义的指针的内存,还是nvcc编译器在程序退出时或者当它超出本地范围时负责解除分配？我不想在我的代码中发生内存泄漏,所以通过解除我之前分配的内存释放感觉更安全.
C.cudaDeviceReset()在renderScene()函数结束时调用是否谨慎,以便根据CUDA C编程指南销毁主CUDA上下文(及其变量和指针)？我已经看到NVidia Visual Profiler doc也提到了这个:cudaDeviceReset()
当我调用它时,渲染似乎比平时慢.如果我能cudaFree在这里简单地记忆,那将是很棒的,但我似乎无法让它发挥作用.
完整代码:
#define GET_PROC_ADDRESS( str ) wglGetProcAddress( str )
GLuint tex;
GLuint pbo;
struct cudaGraphicsResource *cuda_resource;
PFNGLBINDBUFFERARBPROC glBindBuffer = NULL;
PFNGLDELETEBUFFERSARBPROC glDeleteBuffers = NULL;
PFNGLGENBUFFERSARBPROC glGenBuffers = NULL;
PFNGLBUFFERDATAARBPROC glBufferData = NULL;
// ==========================================================================================
// CUDA ERROR CHECKING CODE
#define gpuErrchk(ans) { gpuAssert((ans), __FILE__, __LINE__); }
inline void gpuAssert(cudaError_t code, char *file, int line, bool abort=true)
{
if (code != cudaSuccess)
{
fprintf(stderr,"GPUassert: %s %s %d\n", cudaGetErrorString(code), file, line);
if (abort) getchar();
}
}
// ==========================================================================================
void initCUDADevice() {
gpuErrchk(cudaGLSetGLDevice( cutGetMaxGflopsDeviceId() ));
}
// ==========================================================================================
void changeSize(int w, int h) {
//cudaDeviceReset();
//initCUDADevice();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
// Prevent a divide by zero, when window is too short
// (you cant make a window of zero width).
if (h == 0)
h = 1;
float ratio = w * 1.0 / h;
// Use the Projection Matrix
glMatrixMode(GL_PROJECTION);
// Reset Matrix
//glLoadIdentity();
//// Set the viewport to be the entire window
glViewport(0, 0, w, h);
//// Get Back to the Modelview
glMatrixMode(GL_MODELVIEW);
}
// ==========================================================================================
void renderScene(void) {
// Clear Color and Depth Buffers
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Reset transformations
glLoadIdentity();
// ====================================================================================
// initiate GPU by setting it correctly
//initCUDADevice();
// ====================================================================================
// read the image that needs to be textured
Mat image, flipped;
image = imread("K:/Ultrasound experiment images/PA_175.png", CV_LOAD_IMAGE_GRAYSCALE); // Read the file from disk
if(!image.data) // Check for invalid input
{
cout << "Could not open or find the image" << std::endl ;
}
cv::flip(image, flipped, 0);
imshow("OpenCV - image", image); // displays output
// ====================================================================================
// allocate the PBO, texture, and CUDA resource
glBindBuffer = (PFNGLBINDBUFFERARBPROC)GET_PROC_ADDRESS("glBindBuffer");
glDeleteBuffers = (PFNGLDELETEBUFFERSARBPROC)GET_PROC_ADDRESS("glDeleteBuffers");
glGenBuffers = (PFNGLGENBUFFERSARBPROC)GET_PROC_ADDRESS("glGenBuffers");
glBufferData = (PFNGLBUFFERDATAARBPROC)GET_PROC_ADDRESS("glBufferData");
// ====================================================================================
// generate the pixel buffer object (PBO)
// Generate a buffer ID called a PBO (Pixel Buffer Object)
glGenBuffers(1, &pbo);
// Make this the current UNPACK buffer (OpenGL is state-based)
glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo);
// Allocate data for the buffer. 4-channel 8-bit image
glBufferData(GL_PIXEL_UNPACK_BUFFER, sizeof(unsigned char) * flipped.rows * flipped.cols, NULL, GL_STREAM_DRAW);
glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
gpuErrchk(cudaGraphicsGLRegisterBuffer(&cuda_resource, pbo, cudaGraphicsMapFlagsNone));
// ====================================================================================
// create the texture object
// enable 2D texturing
glEnable(GL_TEXTURE_2D);
// generate and bind the texture
glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_2D, tex);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
// put flipped.data at the end for cpu rendering
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, image.cols, image.rows, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, 0 );
// put tex at the end for cpu rendering
glBindTexture(GL_TEXTURE_2D, 0);
// ====================================================================================
// copy OpenCV flipped image data into the device pointer
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
unsigned char *dev_inp;
gpuErrchk( cudaMalloc((void**)&dev_inp, sizeof(unsigned char)*flipped.rows*flipped.cols) );
gpuErrchk( cudaGraphicsMapResources(1, &cuda_resource, 0) );
size_t size;
gpuErrchk( cudaGraphicsResourceGetMappedPointer((void **)&dev_inp, &size, cuda_resource) );
gpuErrchk( cudaMemcpy(dev_inp, flipped.data, sizeof(unsigned char)*flipped.rows*flipped.cols, cudaMemcpyHostToDevice) );
gpuErrchk( cudaGraphicsUnmapResources(1, &cuda_resource, 0) );
// ====================================================================================
// bind pbo and texture to render data now
glBindBuffer( GL_PIXEL_UNPACK_BUFFER, pbo);
//
glBindTexture(GL_TEXTURE_2D, tex);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, flipped.cols, flipped.rows, GL_LUMINANCE, GL_UNSIGNED_BYTE, NULL);
gpuErrchk( cudaGraphicsUnregisterResource(cuda_resource));
gpuErrchk( cudaThreadSynchronize());
//gpuErrchk(cudaFree(dev_inp));
// ====================================================================================
// map the texture coords to the vertex coords
glBegin(GL_QUADS);
// Front Face
glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f); // Top Right Of The Texture and Quad
glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f); // Top Left Of The Texture and Quad
glEnd();
glFlush(); // force rendering
glDisable(GL_TEXTURE_2D);
//glutSwapBuffers();
gpuErrchk(cudaFree(dev_inp)); // <--- Error here
//cudaGraphicsUnregisterResource(cuda_resource);
}
// ==========================================================================================
int main(int argc, char **argv) {
// init GLUT and create window
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_RGB );
glutInitWindowPosition(100,100);
glutInitWindowSize(1024,256);
glutCreateWindow("CUDA + OpenGL interop");
// register callbacks
glutDisplayFunc(renderScene);
glutReshapeFunc(changeSize);
//glutIdleFunc(renderScene);
// enter GLUT event processing cycle
glutMainLoop();
return 1;
}
此行不是必需的,应从代码中删除:
gpuErrchk( cudaMalloc((void**)&dev_inp, sizeof(unsigned char)*flipped.rows*flipped.cols) );
此行创建设备分配,并为该分配指定指针dev_inp.
问题出现在这里:
gpuErrchk( cudaGraphicsResourceGetMappedPointer((void **)&dev_inp, &size, cuda_resource) );
该行获取一个从该对象派生的新指针cuda_resource到另一个不同的分配,并将该指针放入dev_inp,覆盖以前分配的指针(from cudaMalloc).在此行中获取的新指针已经具有底层设备分配.此时您无需单独/另外分配.
此时,如果您尝试释放dev_inp:
gpuErrchk(cudaFree(dev_inp)); // <--- Error here
您正在尝试释放程序未明确分配的数据(通过cudaMalloc),并且还是持久性(此时)cuda_resource对象的必要组件.你不想那样做.不幸的是,放入的原始指针dev_inp现在丢失(覆盖),因此无法在程序中"释放"它,并且只要程序正在执行,就会发生内存泄漏.
解决方案不是执行额外的,不需要的分配:
gpuErrchk( cudaMalloc((void**)&dev_inp, sizeof(unsigned char)*flipped.rows*flipped.cols) );
这意味着也cudaFree应该消除相应的操作:
gpuErrchk(cudaFree(dev_inp)); // <--- Error here
cudaDeviceReset在程序实际退出之前,我不会在CUDA代码中使用任何地方,特别是CUDA/OpenGL代码.还有一些其他非常特殊的情况,您可能希望cudaDeviceReset在实际意图退出程序之前使用它们,但它们不适用于此处.