Clean CAHCE under Linux

Drop_caches Document Description

Writing to this would cause the kernel to drop clean caches, dentries and inodes from memory, causing that memory to become Free.
To free Pagecache:
* Echo 1 >/proc/sys/vm/drop_caches

To free dentries and inodes:
* Echo 2 >/proc/sys/vm/drop_caches
To free Pagecache, dentries and Inodes:

* Echo 3 >/proc/sys/vm/drop_caches
As this is a non-destructive operation, and dirty objects be notfreeable, the user should run "sync" first in order to Ma ke sure allcached objects is freed.
This tunable is added in 2.6.16.

Clean CAHCE under Linux