LINUX view current system memory usage free

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# Free

The results appear as follows:

Mem: Indicates physical memory statistics

Total Memory 8057964KB
Used memory used 7852484KB
Free amount of memory 205480KB
GKFX is currently obsolete. No, always 0.
Buffersbuffer Cache Memory: 290432KB
Cached Page Cache Memory: 5735024KB
(Existing relationship: total = used + Free)

-/+ buffers/cached: Cache statistics representing physical memory

(-buffers/cache) Used memory: 1827028KB (refers to the first part of the Mem line in the used-buffers-cached)
(+buffers/cache) Free memory: 6230936KB (refers to the first part of the Mem line of Free + buffers + cached)

-buffers/cache reflects the memory that is actually eaten by the program;
+buffers/cache reflects the total amount of memory that can be appropriated;

Swap: Indicates the usage of the swap partition on the hard disk

Free parameter description
-M View memory usage (default is KB) in units of M.
-B View memory usage in bytes
-k View memory usage in kilobytes
-O does not display cache throttling columns
-t display memory sum column
-V Display version information
-S < interval seconds > can not easily monitor memory usage for a specified period of time

The difference between buffers and cached
For an application, buffers/cached is equal to the available
Because buffer/cached is designed to improve the performance of file reads,
The buffer/cached is quickly recycled when the application needs to use memory.
So, from the application's point of view, available memory = System Free memory+buffers+cached.

Buffers refers to the buffer size that is used to make the block device,
He only recorded the file system's metadata and tracking in-flight pages.
Cached is used to buffer files.
That is to say: buffers is used to store, what content inside the directory, permissions and so on.
and cached is directly used to memorize the files we open, if you want to know if he is really effective,
Can try, successively executed two times the command #man X, can obviously feel the second time to fight the speed much faster.

Remember that the memory is for use, not to take a look . Unlike Windows, no matter how much physical memory you have, he will have to take the hard disk swap files to read.
This is why Windows often prompts for a lack of virtual space. You think, how boring, in memory and most of the time, take out a part of
Hard disk space to act as memory. So we look at Linux, as long as we don't swap space, we don't have to worry about our memory.
Too little. If you use a lot of swap, you might want to consider adding physical memory. This is the standard of Linux to see if the memory is adequate.

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LINUX view current system memory usage free