Script - Which User/Process Utilizing High I/O

select 
sid,
username,
round(100 * total_user_io/total_io,2) tot_io_pct
from
(select 
b.sid sid,
nvl(b.username,p.name) username,
sum(value) total_user_io
from 
sys.v_$statname c, 
sys.v_$sesstat a,
sys.v_$session b,
sys.v_$bgprocess p
where 
a.statistic#=c.statistic# and 
p.paddr (+) = b.paddr and
b.sid=a.sid and 
c.name in ('physical reads',
'physical writes',
'physical writes direct',
'physical reads direct',
'physical writes direct (lob)',
'physical reads direct (lob)') 
group by 
b.sid, nvl(b.username,p.name)),
(select 
sum(value) total_io 
from 
sys.v_$statname c, 
sys.v_$sesstat a 
where 
a.statistic#=c.statistic# and 
c.name in ('physical reads',
'physical writes', 
'physical writes direct',
'physical reads direct',
'physical writes direct (lob)',
'physical reads direct (lob)'))
order by 
3 desc
/