oracle cpu per session

1SELECT ss.USERNAME, se.SID, se.VALUE / 100 CPU_USAGE_SECONDS
2FROM V$SESSION ss, V$SESSTAT se, V$STATNAME sn
3WHERE se.STATISTIC# = sn.STATISTIC#
4  AND NAME LIKE '%CPU used by this session%'
5  AND se.SID = ss.SID
6  AND ss.STATUS = 'ACTIVE'
7  AND ss.USERNAME IS NOT NULL
8ORDER BY VALUE DESC;