Re: waits

From: Niall Litchfield <niall.litchfield_at_gmail.com>
Date: Wed, 4 Jan 2012 12:33:28 +0000
Message-ID: <CABe10saWhpieQqfBXFqW+GoVFWvBsd-Et7gE7YCdzgoc6B9W1g_at_mail.gmail.com>

Hi Sidi (?)
This may sound daft, but are you sure you have a problem? I ask because your ADDM extract says - emphasis mine

Symptoms That Led to the Finding:

---

     Wait class "Other" was consuming significant database time.

• Impact is .02 active sessions, 56.98% of total activity. * * * That implies to me that 100% of activity would be 0.035 active sessions - that is 1 second of database activity for about every 28 seconds of wall clock time. That's a pretty idle RAC node! This is one area where I don't like the wording of the ADDM report. I'd prefer

*Wait class "%S" was consuming a significant share of total database time. *

Then it would make it clearer that one also has to look at total database time in relation to the report period.

On Wed, Jan 4, 2012 at 12:04 PM, mek s <sidi.bouzid.meknessy_at_gmail.com>wrote:

> Hello,
> We are getting 100% waits for "Others' event class for instance 1 and
> instance 2 at times in RAC 11.2.0.2.3, 7 nodes environment (Redhat Linux
> 5).
> The ADDM report showing these findings; (see below);
>
> The questions are:
>
> *1- How to identify the root cause of these "other" waits and fix them?*
> *2- How to find the default threshold set for these metrics to see it makes
> sense to increase the threshold?*
> *
> *
> *
> *
>
> Finding 3: Unusual "Other" Wait Event
> Impact is 0 active sessions, 4.92% of total activity.
> ------------------------------------------------
> -----
> Wait event "IPC send completion sync" in wait class "Other" was consuming
> significant database time.
>
> Recommendation 1: Application Analysis
> Estimated benefit is 0 active sessions, 4.92% of total activity.
> -------------------------------------
> ---------------------------
> Action
> Investigate the cause for high "IPC send completion sync" waits. Refer
> to Oracle's "Database Reference" for the description of this wait
> event.
>
> Symptoms That Led to the Finding:
> ---------------------------------
> Wait class "Other" was consuming significant database time.
> Impact is .02 active sessions, 56.98% of total activity.
>
>
> Finding 4: Unusual "Other" Wait Event
> Impact is 0 active sessions, 4.02% of total activity.
> --------------------------------------------
> ---------
> Wait event "enq: PS - contention" in wait class "Other" was consuming
> significant database time.
>
> Recommendation 1: Application Analysis
> Estimated benefit is 0 active sessions, 4.02% of total activity.
> -------------------------------------
> ---------------------------
> Action
> Investigate the cause for high "enq: PS - contention" waits. Refer to
> Oracle's "Database Reference" for the description of this wait event.
>
> Symptoms That Led to the Finding:
> ---------------------------------
> Wait class "Other" was consuming significant da
> tabase time.
> Impact is .02 active sessions, 56.98% of total activity.
>
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

-- 
Niall Litchfield
Oracle DBA
http://www.orawin.info


--
http://www.freelists.org/webpage/oracle-l

Received on Wed Jan 04 2012 - 06:33:28 CST