3rd node is taking 15% of CPU without any load and connection on the server

Question

Hi,
I am struggling to resolve the 3rd node is taking 15% of CPU without any load and connection on the server. but not find clues for this. Please give me some inputs.
The issue is:
We have 8 databases on our 3node RAC (11.2.0.1). One of the performance team guy reported that 3rd node is taking 15%cpu utilization when there is no load and connection to the database and at that time the other 2 node are taking only 1%cpu. even i have checked it by using top command and it is almost given same results.
To come out of this issue, i have two solution in my mind, but i am not sure whether this approach is good or bad. the plans are
(1). shutdown the databases and check the cpu usage. --to findout is there any thing wrong with Kernel parameters or at system level.
(2). Shutdown the databases and CRS on the 3rd node and reboot the server.
If above process is correct then i need to take permission from my manager.
I am total stuck, what i need to do. Is there any other approach to resolve this issue. Please help me, this is very critical issue for me.
Also i have checked from GV$SESSION for the active session, but i didn't find any connection apart from oracle processes.
Thanks in advance.

Answer 1

Thank you Guzma for your suggestion,
When i checked the gv$session for the active sessions from only 2databases, Do i need to check in all the databases and make sure there are no active session and try for the 1st solution.
-more over i have observed that one of the oracle process is taking 99% of the 15%cpu when i checked from top command. i have tried to find out the what the session is from below, but it given no results from the 2of the DB's.
top - 13:43:27 up 28 days, 2:44, 1 user, load average: 8.62, 7.90, 6.46
Tasks: 1275 total, 11 running, 1264 sleeping, 0 stopped, 0 zombie
Cpu(s): 37.3%us, 6.9%sy, 0.0%ni, 44.3%id, 3.9%wa, 0.2%hi, 7.4%si, 0.0%st
Mem: 32830792k total, 32440660k used, 390132k free, 2888k buffers
Swap: 32764556k total, 9553692k used, 23210864k free, 20920068k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
17870 oracle 25 0 4254m 111m 102m R 94.6 0.3 35345:34 oracle
8332 oracle 15 0 9151m 676m 639m R 27.9 2.1 2:03.00 oracle
18062 oracle -2 0 9151m 4.5g 4.5g S 13.5 14.5 3049:49 oracle
18058 oracle -2 0 9151m 4.5g 4.5g S 12.8 14.5 2948:39 oracle
SQL>select p.spid,s.sid,s.serial#,s.username,s.status,s.last_call_et,p.program,p.terminal,logon_time,module,s.osuser
from gV$process p,gV$session s where s.paddr = p.addr and p.spid=17870 ; 2
no rows selected.
in database level, will some of the session or processes hangups fro some reason?
thanks,
Hari