Where did Linux used memory go? __linux

original articles, reproduced please specify: reprinted from the System Technology Amateur research

This article link address: Linux used memory exactly where it went.

A few days ago a pure classmate asked a question:

I PS aux see the RSS memory is less than 30M, but free to see the memory has been used 7,8g, has begun to swap, ask PS aux actual physical memory statistics is not missing which memory is not counted. What can I do to determine where the used memory in free is going?

This problem more than one classmate met, before Zijia classmate also encountered this problem, memory calculation is always a confused account. Let's make it clear today!

This is usually how we look at the rest of the memory:

$free-M

Total used free shared buffers Cached

mem:48262 7913 40349 0 14 267

-/+ buffers/cache:7631 40631

swap:2047 336 1711

So how does this information read, the following diagram explains quite clearly.

Add (many people reflect the picture is not clear, please refer to: Http://www.redbooks.ibm.com/redpapers/pdfs/redp4285.pdf p46-47)

In the case above we have a total of 48262M of memory, used out of 7913M. Buffer+cache Total 14+267=281m, because this type of memory can be recycled, although we used 7913M, but in fact, if we really need, this part of the Buffer/cache memory can be released.

Let's show you the following: