set lines 200
col username for a20
 
select  nvl(ss.USERNAME,'ORACLE PROC') username,
 se.SID,
 VALUE cpu_usage
from  v$session ss, 
 v$sesstat se, 
 v$statname sn
where   se.STATISTIC# = sn.STATISTIC#
and   NAME like '%CPU used by this session%'
and   se.SID = ss.SID
order   by VALUE asc;