这将有效地为数据库共享内存一个段。
This effectively frees up one segment for database Shared memory.
这个总数必须包括文本、数据和栈段，再加上所有的共享内存区域。
This total has to include the text, data, and stack segments, plus all Shared memory regions.
但是，共享内存段不能跨象限“拆分”，而应该保证是一个连续的地址空间。
However, a Shared memory segment cannot be "split" across quadrants and be guaranteed a contiguous address space.
内存区域是已知的作为共享内存的段。
不过，共享内存段依然不能跨越象限边界。
However, Shared memory segments still can not cross quadrant boundaries.
放在这个惟一空间内的共享内存段只能被相同内存窗中的进程访问。
Shared memory segments placed in the unique space can only be accessed by processes within the same memory window.
虽然FCM通信变得更快，但是它也令数据库共享内存减少了一个段。
Though FCM communication becomes faster, it reduces the database Shared memory by one segment.
由于shmseg内核参数被设得太低，有些共享内存段不能适当地分配。
Because SHMSEG kernel parameter is set too low, some Shared memory segments could not be allocated properly.
通信段：共享内存通信区，也被称为消息区，被作为客户机和服务器进程的一种通信机制。
Communications segment: the Shared memory communications portion, also known as the message portion, is used as a communication mechanism by the client and server processes.
在图2中，进程A请求一个共享内存段。
段3-预留给实例共享内存。
该参数按字节指定系统中可以分配的共享内存段的最大大小。
This parameter specifies the maximum size in bytes of a Shared memory segment which can be allocated on the system.
代码实现通过共享内存段通信的父进程和子进程。
The code implements a parent and child process that communicates via a shared memory segment.
动态段分配让用户堆或共享内存可以使用额外的段。
Dynamic segment allocation allows the additional segments to be used by user heap or Shared memory.
现在可以指定创建操作系统平台或者SHMMAX参数所允许的最大共享内存段。
You can now specify that segments for shared memory be created as large as your operating system platform or the SHMMAX parameter allows.
共享内存段要求是连续的，因此不能跨越象限边界。
Shared memory segments are required to be contiguous, and therefore can not be split across quadrant boundaries.
因此，DB2允许分配的最大共享内存段在象限3 中的大小为1GB，在象限4 中的大小为 0.75GB。
Therefore, the largest shared memory segment, in quadrant 3, that DB2 is allowed to allocate is 1GB; and in quadrant 4 is 0.75GB.
顾名思义，共享内存让一段内存可供多个进程访问。
As its name implies, Shared memory makes a segment of memory accessible to more than one process.
SHMMAX 按字节指定系统上可以分配的最大共享内存段。
The SHMMAX specifies the maximum size in bytes of a shared memory segment which can be allocated on the system.
最后，在图4中，进程a和B可以随意读写共享内存段。
Finally, in Figure 4, processes a and B can read and write from the Shared memory segment freely.
内核映射和共享内存段的使用。
POSIX为创建、映射、同步和取消共享内存段提供五个入口点。
POSIX provides five entry points to create, map, synchronize, and undo Shared memory segments.
msync()：用来让共享内存段与文件系统同步 —当把文件映射到内存时，这种技术有用。
msync(): Used to synchronize a shared memory segment with the file system—a technique useful when mapping a file into memory.
shm_unlink()：根据（shm_open()返回的）文件描述符，删除共享内存段。
shm_unlink(): Deletes a shared memory region given a file descriptor (returned from shm_open()).
这表明，进程试图访问因某种原因已破坏的共享内存段，并将不调用“fatal_error”或“panic”而崩溃。
This indicates that the process tried to access a Shared memory segment that was corrupted for some reason, and will crash without calling "fatal_error" or "panic."
shm_open：创建共享内存段或连接到现有的已命名内存段。
Shm_open : Creates a Shared memory region or attaches to an existing, named region.
shmmax按字节指定了系统中可以分配的最大共享内存段。
The shmmax specifies the maximum size in bytes of a Shared memory segment which can be allocated on the system.
从0x10000000到0x3fffffff的段是实例共享内存，总共是0.75GB。
The segment starting from 0x10000000 to 0x3fffffff is the instance Shared memory, for a total of 0.75gb.
这个连接过程称为映射，它给共享内存段分配每个进程的地址空间中的本地地址。
Annexation is called mapping, where the Shared segment of memory is assigned local addresses in each process 'own address space. Figure 1, Figure 2, Figure 3, and Figure 4 depict the process.
shmat失败于0x000000c，即ENOMEM或可用数据空间不足以容纳共享内存段。
Shmat failed because of 0x000000c, which is ENOMEM or the available data space is not large enough to accommodate the Shared memory segment.
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