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Re: wait time is huge compared with cpu time

From: amonte <ax.mount_at_gmail.com>
Date: Sat, 22 Jul 2006 09:45:56 +0200
Message-ID: <85c1fb130607220045i53b6a788i70a10545f9b85019@mail.gmail.com>


Right, it makes sense what page 215 says.

I guess to get the response time using Statspack of a highly loaded system or badly tuned system, which causes massive waits, is not possible. Not even with short interval Snapshots correct? If this is the case the closest REAL response time we can get is with sql trace?

TIA Alex

On 7/21/06, Cary Millsap <cary.millsap_at_hotsos.com> wrote:
>
> If you have a copy of *Optimizing Oracle Performance* handy (Millsap &
> Holt [2003]: O'Reilly), see page 215 for a detailed description of your
> quandary.
>
>
>
>
>
> *Cary** Millsap*
>
> Hotsos Enterprises, Ltd.
>
> http://www.hotsos.com
>
> *Nullius in verba*
>
>
>
> Hotsos Symposium 2007 / March 48 / Dallas
>
> Visit www.hotsos.com for curriculum and schedule details...
> ------------------------------
>
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *amonte
> *Sent:* Friday, July 21, 2006 11:35 AM
>
> *To:* oracle-l_at_freelists.org
> *Subject:* wait time is huge compared with cpu time
>
>
>
> Hi
>
> I have a HP-UX Server running Oracle 8.1.7.4, there are 6 CPUs.
>
> I have a statspack report which shows this (2 hours interval)
>
> Snap Id Snap Time Sessions
> ------- ------------------ --------
> Begin Snap: 143 20-Jul-06 02:31:02 453
> End Snap: 167 20-Jul-06 04:31:06 453
> Elapsed: 120.07 (mins)
>
>
> Top 5 Wait Events
> ~~~~~~~~~~~~~~~~~ Wait %
> Total
> Event Waits Time (cs) Wt
> Time
> -------------------------------------------- ------------ ------------
> -------
> latch free 3,573,965 6,945,555
> 99.25
> log file sync 122,691 30,316
> .43
> log file parallel write 146,604 18,685
> .27
> SQL*Net more data to client 522,539 1,762
> .03
> db file sequential read 10,923 534
> .01
>
>
> Statistic Total per Second per
> Trans
> --------------------------------- ---------------- ------------
> ------------
> CPU used by this session 2,990,059 415.1
> 27.6
> CPU used when call started 2,423,510 336.4
> 22.4
>
>
> I was wondering how can we get over 69000 seconds waits in 2 hours with 6
> CPUs? That is much larger than
>
> 3600seconds * 6CPUs * 2hours
>
> TIA
>
> Alex
>
>
>

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Received on Sat Jul 22 2006 - 02:45:56 CDT

Original text of this message

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