Someone able to answer to this?
I don't understand but my swap seems never to be used after the change. Below is just after reboot.

BusyBox v1.21.0 (1.21.0power1+harmattan0) built-in shell (ash)
Enter 'help' for a list of built-in commands.

~ $ free
total used free shared buffers
Mem: 1008108 688284 319824 0 93476
-/+ buffers: 594808 413300
Swap: 422136 0 422136
~ $ free
total used free shared buffers
Mem: 1008108 702244 305864 0 95688
-/+ buffers: 606556 401552
Swap: 422136 0 422136
~ $ free
total used free shared buffers
Mem: 1008108 750712 257396 0 91228
-/+ buffers: 659484 348624
Swap: 422136 0 422136