find out what is the right block size for SWAP?

i found the following method to create swap, from here

dd if=/dev/zero of=/root/myswapfile bs=1M count=1024

Is there any thumb rule that to decide 开发者_Python百科block size ? What is the best block size for Swap in any machine ? Here it is 1M..

When creating a regular file for swap using dd the blocksize is a convenience to allow the count parameter to create a file of the specified size.

The underlying disk structure is unchanged by the bs= in the dd command.