Which will be better providing the virtual memory (swap) that is to say double the RAM size by manually or choosing w

E.g.: RAM: 512 SWAP (Virtual memory) = 1024

Which will be better providing the virtual memory (swap) that is to say double the RAM size by manually or choosing w

It does not thing, just generate your virtual memory like 1GB.
anything u can do it doesn't concern as i think/.
the paging size can me max 4 times of the memory installed.. usually the virtual memory would not give you the reading as of actual memory
In using your virtual memory it will give you the max amout that the computer will fiddle with. Put it there. The computer will use some of your HD space as memory. Usually it will max out at around 2G.
it does not thing but it is batter to make virsual mamory contained by multipul size of RAM
Can remove unnecessary files in the system & can double the RAM