HOWTO: free up memory

Free Memory by dropping caches | Timesys Embedded Linux

From: http://linux-mm.org/Drop_Caches

To use /proc/sys/vm/drop_caches, just echo a number to it.

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 are not freeable, run sync first!

Here are the before and after results from my desktop:

# free
total used free shared buffers cached
Mem: 2074840 1656052 418788 0 140108 907920
-/+ buffers/cache: 608024 1466816
Swap: 3911816 76436 3835380

# sync ; echo 3 > /proc/sys/vm/drop_caches ; free
total used free shared buffers cached
Mem: 2074840 698472 1376368 0 268 126488
-/+ buffers/cache: 571716 1503124
Swap: 3911816 76436 3835380