Moving memory from swap (page) to RAM

When using more memory than your RAM Linux will use swap which is placed on your hard drive and is much slower. Sometimes after using swap there might be a situation where the RAM is free but some of your data is on the swap. There is a way to relocate the swap data to the RAM.
more details and a nice script to do is are available at: Ubuntu Community Documentation Swap FAQ page.

sudo swapoff -a 

sudo swapon -a

The commands simply shut off swap and turning it on back again.
You'll have to make sure there is enough space on the RAM to accommodate the Swap data, this can be done using:

free 

the output will show you the used space of Swap and free space of RAM:

             total       used       free     shared    buffers     cached
Mem:       8047896     772268    7275628          0      19540     129372
-/+ buffers/cache:     623356    7424540
Swap:     10108920          0   10108920

The example above show that no data (0) is stored on Swap.