V$SESSTAT is a powerful view that has more than 600 counters for every sessions. Class 2 counters are about Redo in this view and you can query which session is writing huge Redo.
There is a query which shows the Number of times a redo entry is copied into the redo log buffer.
select sum(s.value) NumberOfTimesCoppiedLogBuffer,
from v$sesstat s,
where n.statistic# = s.statistic#
and sn.sid = s.sid
and n.name like '%redo entries%'
and sn.type = 'USER'
and sn.sql_id = sq.sql_id
and sq.parsing_schema_name = sn.username
group by sq.sql_id,sn.username
order by NumberOfTimesCoppiedLogBuffer desc;
If you want to use these counters in your performance analysis maybe you want to have a look
Have a nice day.