This is very good new features. If you set Intelligent Data Placement you will gain many performance benefits.

You can set frequently accessed data to hot region. Intelligent Data Placement also allows the placement of primary and mirror extents in different hot or cold regions so if you change this data frequently than set mirror region to hot.
where can i set ?
This settings can be applied for a file or in disk group templates.

if your data files that are accessed at different scenario and your disk groups more than half of full then you must use IDP.

ALTER DISKGROUP DATA ADD TEMPLATE EXAMPLE
ATTRIBUTES ( COLD MIRRORCOLD);

ALTER DISKGROUP DATA MODIFY FILE ‘+data/orcl/datafile/exampl.256.22936765’
ATTRIBUTES (COLD MIRRORCOLD);