Linux system memory Usage Summary __linux

Linux systems can view memory usage through the Cat/proc/meminfo command:
memtotal:3934164 KB
memfree:307128 KB
buffers:148556 KB
cached:1051540 KB
swapcached:213796 KB
active:2309512 KB
inactive:990744 KB
Active (anon): 1710288 KB
Inactive (anon): 458576 KB
Active (file): 599224 KB
Inactive (file): 532168 KB
Unevictable:16 KB
Mlocked:16 KB
swaptotal:3905532 KB
swapfree:2783096 KB
dirty:2248 KB
writeback:0 KB
anonpages:2004748 KB
mapped:77460 KB
shmem:68704 KB
slab:139636 KB
sreclaimable:104656 KB
sunreclaim:34980 KB
kernelstack:3680 KB
pagetables:39604 KB
nfs_unstable:0 KB
bounce:0 KB
writebacktmp:0 KB
commitlimit:5872612 KB
committed_as:4098244 KB
vmalloctotal:34359738367 KB
vmallocused:384644 KB
vmallocchunk:34359330292 KB
hardwarecorrupted:0 KB
hugepages_total:0
hugepages_free:0
hugepages_rsvd:0
hugepages_surp:0
hugepagesize:2048 KB
directmap4k:12288 KB
directmap2m:4067328 KB

The following is an analysis of the various options:

Turn from: http://bbs.chinaunix.net/thread-1929969-1-1.html

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

Memtotal: All available RAM sizes (that is, physical memory minus some reservation bits and the binary size of the kernel)
The sum of Memfree:lowfree and Highfree
Buffers: The buffer size to be used for block devices (only the metadata of the file system and tracking in-flight pages, that is, buffers is used for storage, contents of the directory, permissions, etc.). ）
Cached: Used to buffer the file size (directly to remember the file we opened). It does not include swapcached
Swapcached: Memory that has been swapped out, but is still stored in swapfile. Used to be replaced quickly when needed without having to open the I/O port again.
Active: Memory that is frequently used recently, will not be moved to use unless it is necessary.
Inactive: Memory that is not often used recently, is very useful and may be used in other ways.
Hightotal:
Highfree: High memory refers to all the memory space above 860MB, which is mainly used for user-space programs or cached pages. The kernel must use this memory in a different way, so it is slower than low memory.
Lowtotal:
Lowfree: Low can achieve the same function as high memory, and it can be used by the kernel to record some of its own data structures.
Among many the other things, it's where everything from the slab is
Allocated. Bad things happen the ' re out of Lowmem.

Swaptotal: The sum of the swap spaces
Swapfree: Replaced from RAM for temporary space on disk
Dirty: The amount of memory waiting to be written back to disk.
Writeback: The memory size that is being written back to the disk.
Mapped: The size of the mapping file.
Slab: Kernel Data structure caching
Vmalloctotal:vmalloc Memory Size
Vmallocused: The size of the virtual memory that has been used.
Vmallocchunk:largest contigious block of Vmalloc area which are free

Commitlimit:
Committed_as:

Linux Memory calculation method:

1, Memtotal value as total memory

2, free memory calculation mode: If cached value is greater than memtotal value, then free memory is memfree value, otherwise free memory is Memfree value +buffers value +cached values

3, Memory usage is: free memory/Total memory *100%.