CPU Usage By Session

select nvl(ss.USERNAME,'ORACLE PROC'),
se.SID,
VALUE
from sys.v_$session ss, sys.v_$sesstat se, sys.v_$statname sn
where se.STATISTIC# = sn.STATISTIC#
and NAME like '%CPU used by this session%'
and se.SID = ss.SID
order by VALUE desc;