mmap mindmap

http://blog.csdn.net/chenjin_zhong/article/details/6314213 1. Memory Mapping The so-called memory mapping is to map physical memory into the process's address space, these applications can directly use the input and output of the address space, so as to improve the efficiency of reading and writing. Linux provides the mmap () function to map physical memory. In the driver, the application takes a device file as an object, invokes the

Linux c development-Memory Manager ptmallocMemory Layout To understand the ptmalloc Memory Manager, you must first understand the memory layout of the operating system. The following figure shows the Memory Distribution of stacks and stacks. X86 LINUX Process Memory layout: Is the memory layout of the linux operating system. The memory distribution of each module in the operating system is displayed from low to high. Test Segment: stores program code. It is read-only and determined during compi

two fragment to start playing. In this way, you can increase the buffer size by increasing the number of fragment, but each fragment is limited to an appropriate size without affecting the latency. Generally, the multi-buffer mechanism in the audio driver uses the scatter-gather function of the base layer DMA controller. On the other hand, the application can also instruct the driver to select a buffer of the appropriate size, so that the latency is as small as possible without jitter. In part

. It doesn't matter as long as it is not ineffective, you still don't need to improve it. Remember, TestCase is not your product, it should not look good, it should not be too scientific, or even have no performance requirements, as long as it can fulfill its mission, it also proves the feasibility of "Writing Test Cases with Ctrl-C/Ctrl-V. However, the idea of Americans is actually not the same as that of us. Take the MindMap of Tony Barzan as an exa

Zheng @ playfun RT 20090714 1. Case study of Twitter Neural Network Last week, I saw an article "Twitter (data) as a neural network" from playlist Sr. The author made a detailed analysis on the propagation path of a twitter message, A node chart, timeline, latency time chart, and followings number chart are provided. The following figure lists the message propagation processes: User; Forwarding time; User followings/followers number; Who will pass it; . The data mini

When our iMindMap Mind Map branch is too large, we should consider moving some of the branches out for new ones, but the re-operation is obviously cumbersome. Wit like me, found iMindMap One of the sub-map conversion function, a key to do, the following small series to see the operation of it.If you have any questions, you can visit: http://www.imindmap.cc/imp-cj-zidaotu.htmlWe open the iMindMap mind map drawing, or open the existing iMindMap file directly, select the

1. What is video4linux?Video4linux (v4l for short) is the kernel driver for video devices in Linux.Video4linux2 is now available and has not been added to the Linux kernel. You need to download the patch by yourself.In Linux, a video device is a device file that can be read and written just like a common file.The camera is under/dev/video0. 2. Video programming process in video4linux1. Enable the video device:2. Read Device Information3. Change the current device settings (if necessary)4. Two Me

of some video systems, video software, and audio software. It is often used in scenarios where images need to be collected, such as video surveillance, webcam, and videophone, often used in Embedded Linux is a commonly used system interface in Linux embedded development. It is a programming interface provided by the Linux kernel to the user space. After various video and audio devices develop corresponding drivers, they can control the video and audio devices through the system APIs provided by

Series of articles directory: http://blog.csdn.net/wylblq/article/details/51841684 4.3 Storage mappingsPOSIX provides related calls that allow us to map files into memory, which allows us to easily read file data from memory, modify in-memory data to change the contents of a file, or implement inter-parent interprocess communication.4.3.1 mmap ()#include void *mmap(voidlengthintintint fd, off_t offset)

Linux kernel State and user state shared memory 1. Mmap system call (function)void* mmap (void * addr, size_t len, int prot, int flags, int fd, off_t offset)Memory-mapped function mmap, which is responsible for mapping the contents of the file to the virtual memory space of the process, by reading and modifying the memory, to realize the reading and modification

]; Struct video_picture picture; Struct video_clip clip; Struct video_window window; Struct video_capture capture; Struct video_buffer buffer; Struct video_mmap MMAP; Struct video_mbuf mbuf; Struct video_unit unit; Unsigned char * map; // The first address of the data when the MMAP method is used to obtain data. Pthread_mutex_t mutex; Int frame; Int framestat [2]; Int overlay; } V4ldevice; /* The followi