Re: wait time is huge compared with cpu time

  • From: "LS Cheng" <exriscer@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Sun, 23 Jul 2006 11:16:50 +0200

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@xxxxxxxxx> 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@xxxxxxxxxx> 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 4–8 / Dallas
>
> Visit www.hotsos.com for curriculum and schedule details...
>  ------------------------------
>
> *From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx
> ] *On Behalf Of *amonte
> *Sent:* Friday, July 21, 2006 11:35 AM
>
> *To:* oracle-l@xxxxxxxxxxxxx
> *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
>
>
>

Other related posts: