Linux 下meminfo 详解

         在内核的文档中Documentation/filesystems/proc.txt中关于meminfo的解释如下：

meminfo:

Provides information about distribution and utilization of memory.  This
varies by architecture and compile options.  The following is from a
16GB PIII, which has highmem enabled.  You may not have all of these fields.

> cat /proc/meminfo

MemTotal:     16344972 kB
MemFree:      13634064 kB
Buffers:          3656 kB
Cached:        1195708 kB
SwapCached:          0 kB
Active:         891636 kB
Inactive:      1077224 kB
HighTotal:    15597528 kB
HighFree:     13629632 kB
LowTotal:       747444 kB
LowFree:          4432 kB
SwapTotal:           0 kB
SwapFree:            0 kB
Dirty:             968 kB
Writeback:           0 kB
Mapped:         280372 kB
Slab:           684068 kB
CommitLimit:   7669796 kB
Committed_AS:   100056 kB
PageTables:      24448 kB
VmallocTotal:   112216 kB
VmallocUsed:       428 kB
VmallocChunk:   111088 kB

相应选项中文意思想各位高手已经知道，如何翻译有什么错误，请务必指出：

    MemTotal: 所有可用RAM大小 （即物理内存减去一些预留位和内核的二进制代码大小）

     MemFree: LowFree与HighFree的总和

     Buffers: 用来给块设备做的缓冲大小（只记录文件系统的metadata以及 tracking in-flight pages，就是说 buffers是用来存储，目录里面有什么内容，权限等等。）

      Cached: 用来给文件做缓冲大小（直接用来记忆我们打开的文件）. 它不包括SwapCached

  SwapCached: 已经被交换出来的内存，但仍然被存放在swapfile中。用来在需要的时候很快的被替换而不需要再次打开I/O端口。

      Active: 最近经常被使用的内存，除非非常必要否则不会被移作他用.

    Inactive: 最近不经常被使用的内存，非常用可能被用于其他途径.

   HighTotal:
    HighFree: 高位内存是指所有在860MB以上的内存空间，该区域主要用于用户空间的程序或者是缓存页面。内核必须使用不同的手法使用该段内存，因此它比低位内存要慢一些。

    LowTotal:
     LowFree: 低位可以达到高位内存一样的作用，而且它还能够被内核用来记录一些自己的数据结构。     Among many
              other things, it is where everything from the Slab is
              allocated.  Bad things happen when you're out of lowmem.

   SwapTotal: 交换空间的总和

    SwapFree: 从RAM中被替换出暂时存在磁盘上的空间大小

       Dirty: 等待被写回到磁盘的内存大小。

   Writeback: 正在被写回到磁盘的内存大小。

      Mapped: 影射文件的大小。

        Slab: 内核数据结构缓存

 CommitLimit: Based on the overcommit ratio ('vm.overcommit_ratio'),
              this is the total amount of  memory currently available to
              be allocated on the system. This limit is only adhered to
              if strict overcommit accounting is enabled (mode 2 in
              'vm.overcommit_memory').
              The CommitLimit is calculated with the following formula:
              CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap
              For example, on a system with 1G of physical RAM and 7G
              of swap with a `vm.overcommit_ratio` of 30 it would
              yield a CommitLimit of 7.3G.
              For more details, see the memory overcommit documentation
              in vm/overcommit-accounting.
Committed_AS: The amount of memory presently allocated on the system.
              The committed memory is a sum of all of the memory which
              has been allocated by processes, even if it has not been
              "used" by them as of yet. A process which malloc()'s 1G
              of memory, but only touches 300M of it will only show up
              as using 300M of memory even if it has the address space
              allocated for the entire 1G. This 1G is memory which has
              been "committed" to by the VM and can be used at any time
              by the allocating application. With strict overcommit
              enabled on the system (mode 2 in 'vm.overcommit_memory'),
              allocations which would exceed the CommitLimit (detailed
              above) will not be permitted. This is useful if one needs
              to guarantee that processes will not fail due to lack of
              memory once that memory has been successfully allocated.
  PageTables: amount of memory dedicated to the lowest level of page
              tables.

VmallocTotal: vmalloc内存大小

 VmallocUsed: 已经被使用的虚拟内存大小。

VmallocChunk: largest contigious block of vmalloc area which is free