Hello,
Yesterday, one of our database server CPU host jumped from about 20% to 100% for more than one hour. top command revealed that it is a user processes instead of a system processes that hogged all of the cpu. I/O and memory appeared to be OK. I've tried to capture about the top 10 processes and it all belong to this database but it keep changing anyway. I've looked at some of the queries belong to those top processes, but it is a simple queries that would not hog all the cpu. But, the top processes keep changing all the time instead of fix for long period of time. I've looked at v$session_longops where sofar<totalwork and nothing show up except one process that already finish. Addm report top recommendation is to add more cpu. After about one hour, cpu was back down to 20% and I don't know what going on. Attached is a portion of awrddrpt for good (1st) and bad time (2nd). For security reason, I've removed all sql statements. This problem has happened twice in the past and appeared to be random and I know it will happen again.
Thank you for any assistance. I am not a awr expert.