RE: CPU Wait troubleshoot

From: Powell, Mark <mark.powell2_at_hpe.com>
Date: Tue, 12 Apr 2016 19:17:41 +0000
Message-ID: <1E24812FBE5611419EFAFC488D7CCDD132AEEFC3_at_G4W3290.americas.hpqcorp.net>

Is PQO in use on your system? The submission of a query which gets/demands a very high degree of parallelism can cause a spike in CPU while the query slaves are launched and running.

What does the ASH report show for this time period? If the information is anywhere I would think this is the place to look.

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Martin Berger Sent: Tuesday, April 12, 2016 1:41 PM
To: backseatdba_at_gmail.com
Cc: oracle-l_at_freelists.org
Subject: Re: CPU Wait troubleshoot

Jeff,
Spikes in graphs which show averages are ... dangerous. But nevertheless you should be able to identify "something" those sessions have in common. My first checks are sql_id, or program/action/module/... (your application is properly instrumented?) or in general anything you can use to identify why these sessions are special, especially in comparison to the "ordinary" 2-5 active sessions. If you find anything special in those sessions, we all together can drill down to explain what's going on in your system.  Martin

2016-04-12 19:16 GMT+02:00 Jeff Chirco <backseatdba_at_gmail.com<mailto:backseatdba_at_gmail.com>>: Looking for some help on how to troubleshoot this spike in CPU Wait. Every so often it will see this large spike and I am not sure how to find out what it is related to or why it is happening. It spike up to 400 active sessions when normally we only around 2 - 5. When I click on the graph to drill in it only show the CPU usage and nothing near 400 active sessions. What else do I need to look out to figure this out. Thanks in advanced.

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Jeff

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Received on Tue Apr 12 2016 - 21:17:41 CEST