Perhaps you're right, looking at slide 19/53, the 4th bullet points states: • => wait event times are artificially inflated If I look at non peak and peak wait events for my awr I see: Non Peak: Event Waits Time(s) Avg Wait(ms) % Total Call Time Wait Class CPU time 4,262 20.8 db file sequential read 320,813 3,726 12 18.2 User I/O db file scattered read 422,587 3,239 8 15.8 User I/O gc buffer busy 373,929 2,265 6 11.0 Cluster db file parallel read 38,122 1,992 52 9.7 User I/O Peak: Event Waits Time(s) Avg Wait(ms) % Total Call Time Wait Class gc buffer busy 986,001 95,686 97 37.0 Cluster enq: TX - index contention 200,074 49,370 247 19.1 Concurrency buffer busy waits 285,277 19,594 69 7.6 Concurrency gc cr multi block request 1,251,468 11,719 9 4.5 Cluster enq: SQ - contention 47,491 10,044 212 3.9 Configuration GC Buffer Busy has jumped right to the top, CPU time is no where to be seen, but I know during this 30 minute snapshot with 8 cores I have 30x8x60=14400 --> BUSY_TIME 1,046,108 104610/14440 x100= 72.4% The same slide says tune for CPU , before waits when CPU constrained - guess that mean I shouldn't focus on determining the segment/segment type that might be causing contention? ________________________________ From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx> To: "oracledbawannabe@xxxxxxxxx" <oracledbawannabe@xxxxxxxxx>; "harel.safra@xxxxxxxxx" <harel.safra@xxxxxxxxx>; "Oracle-L@xxxxxxxxxxxxx" <Oracle-L@xxxxxxxxxxxxx> Sent: Wed, November 24, 2010 11:12:08 PM Subject: RE: CPU Per Exec - SQL Ordered By CPU Time I’m not sure on this – I thought that time waiting in the CPU run queue was included in the v$sql.cpu_time and “CPU used by this session” stats, but according to slide 20 here, it looks like maybe the time in the CPU run queue is actually accounted for in the IO wait event instead: http://www.oracle.com/technetwork/database/features/manageability/db-perf-tuning-ow08-131582.pdf ________________________________ Privileged/Confidential Information may be contained in this message or attachments hereto. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of this company shall be understood as neither given nor endorsed by it.