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RE: wait time is huge compared with cpu time

Khemmanivanh, Somckit

2006-07-21

Replies:

Could maybe be a by product of when transactions completed. Remember that the recording is made when the transaction completes...so timing wise a long running transaction could have just completed when you began the snap?
 

 

From: oracle-l-bounce@freelists.org [mailto:oracle-l-bounce@freelists.org] On Behalf Of amonte
Sent: Friday, July 21, 2006 9:35 AM
To: oracle-l@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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