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zh:manual:appendix:items:vm.memory.size_params
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2 参数vm.memory.size
- total - 总物理内存.
- free - 可用内存.
- active - 内存当前使用或最近使用，所以它在RAM中。
- inactive - 未使用内存.
- wired - 被标记为始终驻留在RAM中的内存，不会移动到磁盘。
- pinned - 和'wired'一样。
- anon - 与文件无关的内存(不能重新读取)。
- exec - 可执行代码，通常来自于一个(程序)文件。
- file - 缓存最近访问文件的目录。
- buffers - 缓存文件系统元数据。
- cached - 缓存为不同事情。
- shared - 可以同时被多个进程访问的内存。
- used - active + wired 内存。
- pused - active + wired 总内存的百分比。
- available - inactive + cached + free 内存。
- pavailable - inactive + cached + free memory 占'total'的百分比。
vm.memory.size[used] 和 vm.memory.size[available] 的和不是必需等于总内存。 例如, 在FreeBSD中 active, inactive, wired, cached被认为是使用的内存， 因为他们存储一些有用的信息。
同样，inactive, cached, free 也被认为是可用内存， 因为这些内存可以立即被分配给需要更多内存的线程。
所以不活动的内存是同时可以是使用和可用的。 正因为如此, item vm.memory.size[used] 只用来获得信息, 监控项 vm.memory.size[available] 在触发器中使用。
同样，inactive, cached, free 也被认为是可用内存， 因为这些内存可以立即被分配给需要更多内存的线程。
所以不活动的内存是同时可以是使用和可用的。 正因为如此, item vm.memory.size[used] 只用来获得信息, 监控项 vm.memory.size[available] 在触发器中使用。
参看本页底部 "另外见" 部分关于在不同的操作系统中内存计算的更多详细信息。
特定系统的注意事项
- 在Solaris中 available and free 是一样的。
- 在Linux中 shared 只在 kernel 2.4中起作用。
另见
2 vm.memory.size parameters
Overview
This section provides more details and platform-specific information on the parameters of the vm.memory.size[<mode>] agent item.
Parameters
The following parameters are possible for this item:
- active - memory currently in use or very recently used, and so it is in RAM
- anon - memory not associated with a file (cannot be re-read from it)
- available - available memory, calculated differently depending on the platform (see the table below)
- buffers - cache for things like file system metadata
- cached - cache for various things
- exec - executable code, typically from a (program) file
- file - cache for contents of recently accessed files
- free - memory that is readily available to any entity requesting memory
- inactive - memory that is marked as not used
- pavailable - inactive + cached + free memory as percentage of 'total'
- pinned - same as 'wired'
- pused - active + wired memory as percentage of 'total'
- shared - memory that may be simultaneously accessed by multiple processes
- slab - total amount of memory used by the kernel to cache data structures for its own use
- total - total physical memory available
- used - used memory, calculated differently depending on the platform (see the table below)
- wired - memory that is marked to always stay in RAM. It is never moved to disk.
Platform-specific calculation of available and used:
| Platform | “available” | “used” |
|---|---|---|
| AIX | free + cached | real memory in use |
| FreeBSD | inactive + cached + free | active + wired + cached |
| HP UX | free | total - free |
| Linux<3.14 | free + buffers | total - free |
| Linux 3.14+ | /proc/meminfo, “Cached”:+“MemAvailable:” | total - free |
| NetBSD | inactive + execpages + file + free | total - free |
| OpenBSD | inactive + free + cached | active + wired |
| OSX | inactive + free | active + wired |
| Solaris | free | total - free |
| Win32 | free | total - free |
The sum of vm.memory.size[used] and vm.memory.size[available] does not necessarily equal total. For instance, on FreeBSD:
* Active, inactive, wired, cached memories are considered used, because they store some useful information.
* At the same time inactive, cached, free memories are considered available, because these kinds of memories can be given instantly to processes that request more memory.
So inactive memory is both used and available simultaneously. Because of this, the vm.memory.size[used] item is designed for informational purposes only, while vm.memory.size[available] is designed to be used in triggers.
* Active, inactive, wired, cached memories are considered used, because they store some useful information.
* At the same time inactive, cached, free memories are considered available, because these kinds of memories can be given instantly to processes that request more memory.
So inactive memory is both used and available simultaneously. Because of this, the vm.memory.size[used] item is designed for informational purposes only, while vm.memory.size[available] is designed to be used in triggers.
See the "See also" section at the bottom of this page to find more detailed information about memory calculation in different OS.
Platform-specific notes
- on Linux shared works only on kernel 2.4