You cannot view the shared memory files ( commonly referred as shm files) by using the cat utility generally used for file display in Linux since these shm files are in a binary format. 在Linux系统中,您不能通过使用通常用于文件显示的cat实用工具来查看共享内存文件(常指的是shm文件),因为这些shm文件是以二进制的格式存储的。
So, while/ tmp/ foo would map to/ dev/ shm/ tmp/ foo, there's no way for you to access the/ dev/ shm/ bar file from/ tmp. 所以,虽然/tmp/foo会映射到/dev/shm/tmp/foo,但您没有办法从/tmp访问/dev/shm/bar文件。
This system call requires the file descriptor from shm_open() and returns a pointer to memory. 这个系统调用需要shmopen()返回的文件描述符,它返回指向内存的指针。
However, once shm_unlink() is called ( typically by the originating process), no other processes can access the region. 但是,调用shmunlink()(通常由原来创建共享内存段的进程调用)之后,其他进程就无法访问这个内存段了。
However, while you could bind mount/ dev/ shm to/ tmp and be done with it, your/ dev/ shm contains some directories that you don't want to appear in/ tmp. 然而,虽然您可以在/tmp绑定安装/dev/shm就完成了,但您的/dev/shm还包含一些您不想在/tmp出现的目录。
To finish, the originating process calls munmap() and shm_unlink(), and then exits. 当使用完时,原来的进程调用munmap()和shmunlink(),然后退出。
Shm_unlink(): Deletes a shared memory region given a file descriptor ( returned from shm_open()). shmunlink():根据(shmopen()返回的)文件描述符,删除共享内存段。
Now that our directory is ready, we can mount/ dev/ shm/ tmp, and only/ dev/ shm/ tmp to/ tmp. 既然我们的目录已经准备好了,我们可以安装,也只能安装/dev/shm/tmp到/tmp。
To learn more about shared memory (/ dev/ shm) and its use, check out this practical tutorial on/ dev/ shm. 要了解更多有关共享内存(/dev/shm)及其使用的信息,请查阅这个实用教程。
The client process implementation is in shm_client.cpp 客户机进程的实现在shmclient.cpp中
Shm_client2 ( essentially a copy of shm_client1) will use PollForEvents() as follows shmclient2(实际上是shmclient1的一个拷贝)会使用PollForEvents()方法,如下所示
When you run the shm_client, you should get the following output 在运行shmclient时,应该可以看到下面的输出
Eaccelerator.shm_size defines the size of the shared memory cache, which is where the compiled scripts are stored. shmsize定义共享高速缓存的大小,编译后的脚本就存储在这里。
Each program creates its own file; in my examples, I use the file name devmem located at/ dev/ shm/ devmem. 每个程序都会创建自己的文件;在文本的示例中,我使用的文件名为dumpmem,位于/dev/shm/dumpmem。
Otherwise, vs1 init scripts won't be able to create the/ dev/ shm/ network directory it uses while setting up the network. 否则,vs1init脚本将不能在设置网络时创建需要使用的/dev/shm/network目录。
The call to shm_open() should look familiar; it is much like the open() function, including how to initialize the segment and permissions. 对shmopen()的调用看起来应该很熟悉;它与open()函数很相似,包括初始化内存段和设置权限的方式。
This will cause the tmpfs filesystem mounted at/ dev/ shm to carry the vs1 label so that vs1 can write to it. 这导致在/dev/shm上装载tmpfs文件系统,以带上vs1标签,从而让vs1可以对它执行写操作。
Dev/ shm is an implementation of the traditional shared memory concept. dev/shm是传统共享内容概念的实现。
SHM VP: Handles the task of polling for new connections when the application is using the shared memory method of communication. SHMVP:当应用程序正在使用通信的共享内存方法时,该类将为新连接处理轮询任务。
In/ dev/ shm, one program or daemon creates a memory portion that other processes ( at relevant permission levels) can access. 在/dev/shm中,一个程序或守护程序创建其他进程(具有相关的权限级别)可以访问的内存区。
The memory file storage is/ dev/ shm/ devmem 内存文件存储是/dev/shm/dumpmem
This time, instead of mounting our new tmpfs filesystem at/ mnt/ tmpfs, we created it at/ dev/ shm, which is a directory that happens to be the "official" mountpoint for a tmpfs filesystem. 这次,我们没有把tmpfs文件系统安装在/mnt/tmpfs,而是创建在/dev/shm,这正好是tmpfs文件系统的“正式”安装点。
Let's say that you have a tmpfs filesystem mounted at/ dev/ shm, its traditional location, and you decide that you'd like to start using tmpfs for/ tmp, which currently lives on your root filesystem. 假设您有一个tmpfs文件系统安装在它的传统位置/dev/shm,您决定要开始在当前位于根文件系统的/tmp使用tmpfs。
The/ dev/ shm implementation of traditional shared memory 传统共享内存的/dev/shm实现
Because no shared objects are present, it creates them, references their data members, invokes their virtual functions, and quits& leaving the objects behind in memory. 由于现在没有共享对象,于是shmclient1创建了它们,引用它们的数据成员,调用它们的虚函数,然后退出&将对象留在了内存中。
The shared library implementation is in shm_server.cpp 共享库的实现在shmserver.cpp中
Research on Monitoring Data Processing Method About Long-span Cable-stayed Bridge SHM System 大跨斜拉桥结构健康监测系统数据处理方法研究
C, shared memory in ipc/ shm. c中实现,共享内存在ipc/shm。
Phase is important quantity for describing shm. 相位是描述简谐振动的重要的物理量。
Frequency response method used in Structure Health Monitoring ( SHM) system is discussed in this article. 本文就频率响应方法在结构健康监测系统中的应用进行研究。