mmap example

1. An error is reported when ORACLE software is installed to 86%. The figure is missing. The log is as follows: /Oracle/u01/app/oracle/product/11.2.0/INFO: db_1/lib/sysliblist '-R/opt/SUNWcluster/lib-R/export/home/oracle/u01/app/oracle/product/11.2.0/db_1/lib-R/opt /ORCLcluster/lib/-y p, :/opt/SUNWcluster/lib:/opt/ORCLcluster/lib/:/usr/ccs/lib/amd64: /usr/lib/amd64-Qy-lm/export/home/oracle/u01/app/oracle/product/11.2.0/db_1/lib/prod/lib/amd64/crtn. o-lpthread INFO: ld: fatal:

"Dynamic MMap has no space. Please increase the resolution of APT: Cache-Limit... ". when updating the software in javastun, the following error occurs: Java code jiyj @ ubuntu :~ $ Sudo apt-get install firefox [sudo] password for jiyj: Sorry, try again. [sudo] password for jiyj: www.2cto.com is reading the package list... An error occurred! E: Dynamic MMap has no space. Increase the size of APT: Cache-Limi

Best references: 1. Master from the Internet. 2. UNP V2 posix ipc chapter 12. 3. Linux man command. Article 1: MMAP function Purpose 1. Map common files to the process memory space for memory ing Io. 2. Map special files to the process memory space for anonymous memory ing Io. 3. Map shm_open to open the POSIX shared memory zone to the memory space of the process, which can provide data sharing and IO among unrelated processes. # Include V

The video application can apply for a buffer from the v4l2 driver in two ways. 1. userptr, as the name implies, refers to the user space pointer. the application layer allocates the required memory space and passes it to the v4l2 driver layer as a pointer, the v4l2 driver saves the content of capture to the space indicated by the pointer. In general, the application layer needs to ensure that the memory space is physically consecutive (the IPU processing unit is required), and the Android syst

(n_buffers = 0; n_buffers {Struct v4l2_buffer Buf; // one frame in the driverClear (BUF );Buf. type = v4l2_buf_type_video_capture;Buf. Memory = v4l2_memory_mmap;Buf. Index = n_buffers; If (-1 = IOCTL (FD, vidioc_querybuf, BUF) // map the user spacePrintf ("vidioc_querybuf error \ n "); Buffers [n_buffers]. Length = Buf. length;Buffers [n_buffers]. Start =MMAP (null/* start anywhere */, // establishes a ing through MMAPBuf. length,Prot_read | prot_wr

Copy_to_user needs to check the validity of the pointer during each copy, that is, the pointer to the address of the user space is indeed the address of the process itself, instead of pointing to the location that does not belong to it, in addition, data is copied once each time, and memory is frequently accessed. Because the virtual address is continuous, the physical address may not necessarily be consecutive, resulting in frequent cache failures of the CPU, thus reducing the speed.MMAP only c

Dynamically passes the physical address and size of the kernel space to user space. This article also demonstrates two common methods that can be used for communication between kernel space and user space: Proc file system and Mmap shared memory.The entire kernel module, when the module inserts, establishes the proc file, allocates the memory. When the module is unloaded, the content written by the user space is printed.Here is the code for the kernel

space to map;Flags: Flags to map the IO space and permissions;function: Mapping an IO address space to the virtual address space of the kernel for easy access;implementation: To determine the IO address space to be mapped, the low Pci/isa address does not need to be remapped, does not allow the user to map the IO address space to the RAM in use, and finally applies a vm_area_struct structure, calling Remap_area_ Pages fill in the page table, if the completion process is unsuccessful, release th

View MySQL LogsInnodb:initializing buffer pool, size =128.0MInnodb:mmap (137363456bytes) failed; Errno Ainnodb:completed Initialization of buffer poolinnodb:fatal Error:cannot allocate memory forThe buffer Pool[error] Plugin'InnoDB'Initfunctionreturned error. [ERROR] Plugin'InnoDB'registration as a STORAGE ENGINE failed. [ERROR] Unknown/Unsupported storage engine:innodb[error] abortingToo few caches. free-m total used free shared buffers Cachedmem: 11

Note: This example uses the form of shared file ing. The write end writes data and the read end reads data. Write end: /*-------------map_normalfile1.c-----------*/#include Read end: /*-------------map_normalfile2.c-----------*/#include

I. overview memory ing: in short, you can map a memory area of your space to the kernel space. After the ing is successful, your modifications to this memory area can be directly reflected in the kernel space. On the contrary, modifications made to

Overview of Shared memory The shared memory area is the fastest form of IPC, where data delivery is no longer related to the kernel, in other words, processes no longer pass data to each other by executing system calls into the kernel. That is,

Shared memory can be said to be the most useful interprocess communication and the fastest form of IPC because processes can read and write directly to memory without requiring any copy of the data. For communication like pipelines and Message

I. overview memory ing: in short, you can map a memory area of your space to the kernel space. after the ING is successful, your modifications to this memory area can be directly reflected in the kernel space. On the contrary, modifications made to

    Ffi = require 'ffi' ffi. cdef [[ int open (const char * file, int flag); void * mmap (void * _ addr, int _ len, int _ prot, int _ flags, int _ fd, int _ offset); # pragma pack (1) typedef struct { char name [21]; unsigned short age;

driver as an example to implement the mapping. For more information about character device drivers, refer to the author of this article: http://blog.csdn.net/shallnet/article/details/17734309The key to implementing memory mapping is to implement the character device-driven mmap () function, and the mmap () function prototype is:#include This function is respon

. At this point the H value is generated from the path address of the file, and the path here is an absolute path. Even if you are using a relative path, you will find the PG (include_path) location file to get an absolute path, so skipping the check using an absolute path can improve the efficiency of your code.Adding caching proceduresIn user caching, for example, the Apc_add function is used to add content to the APC cache. If the key argument is a

Python decorator use example and actual application example, python example Test 1 Deco is running, but myfunc is not running Copy codeThe Code is as follows:Def deco (func ):Print 'before func'Return func Def myfunc ():Print 'myfunc () called'Myfunc = deco (myfunc) Test 2 Call myfunc in the required deco to executeCopy codeThe Code is as follows:Def deco (func

/*====================================================================== A Globalmem Driver As an example of char device drivers There are two same globalmems in this driver This example was to introduce the function of File->private_data The initial developer of the original code is Baohua Song ======================================================================*/ #include #include #include #include #in

apc.php for monitoring and managing the APC cache. (Note: Modify administrator name and password) 3.APC The default is to create shared memory by Mmap Anonymous mappings, which are stored in this large memory space. This shared memory is managed by the APC itself 4. Adjust the value of Apc.shm_size, Apc.num_files_hints, Apc.user_entires_hint to the best 5.php predefined constants, you can use the APC _define--constants () function. However, APC devel