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Re: wait time is huge compared with cpu time

From: LS Cheng <exriscer_at_gmail.com>
Date: Sun, 23 Jul 2006 11:16:50 +0200
Message-ID: <6e9345580607230216k1d078c81gf7a690f372267825@mail.gmail.com>


Hi Alex

You cant really get the response time from Statspack a per session fashion. In your report I presume there must be hundredes of waiting sessions correct?

On 7/22/06, amonte <ax.mount_at_gmail.com> wrote:
>
> 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 Sun Jul 23 2006 - 04:16:50 CDT

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