Re: waits
From: Niall Litchfield <niall.litchfield_at_gmail.com>
Date: Wed, 4 Jan 2012 13:30:40 +0000
Message-ID: <CABe10sbg4HJpm+58_OW_uU47oToshe1ZU-5LJ9E8PYiQrFdiHw_at_mail.gmail.com>
The threshold is set in terms of contributions to the time model statistic "db time" which is essentially non-idle database work expressed in seconds (active sessions can be thought of as db time per second). There will always be some DB Time, and then there will always be a breakdown of that activity. I wouldn't be wanting to delve too much into the actual thresholds (which is why I don't know what they are off hand) but I definitely would be interested in either
Date: Wed, 4 Jan 2012 13:30:40 +0000
Message-ID: <CABe10sbg4HJpm+58_OW_uU47oToshe1ZU-5LJ9E8PYiQrFdiHw_at_mail.gmail.com>
The threshold is set in terms of contributions to the time model statistic "db time" which is essentially non-idle database work expressed in seconds (active sessions can be thought of as db time per second). There will always be some DB Time, and then there will always be a breakdown of that activity. I wouldn't be wanting to delve too much into the actual thresholds (which is why I don't know what they are off hand) but I definitely would be interested in either
- responding to complaints about poor performance from users in terms of "where does the time go"
- generally ensuring that DB Time per Second is at a reasonable level ( < n seconds per second where n is the cpu core count is my rule of thumb).
Rule 1 above trumps rule 2. Always.
So I wouldn't be changing thresholds, but I would be keeping communication channels open with my users and sanity checking ADDM reports against the period of time for which they report.
HTH On Wed, Jan 4, 2012 at 12:47 PM, mek s <sidi.bouzid.meknessy_at_gmail.com>wrote:
> Thanks very much Niall, ; this is a recently installed RAC environment and
> recently pushed in production.
> One more question; How to find the default threshold set for these metrics
> to see it makes sense to increase the threshold?
>
-- Niall Litchfield Oracle DBA http://www.orawin.info -- http://www.freelists.org/webpage/oracle-lReceived on Wed Jan 04 2012 - 07:30:40 CST