Re: CPU Time

  • From: Jaffar_DBA <sjaffarhussain@xxxxxxxxx>
  • To: jonathan@xxxxxxxxxxxxxxxxxx
  • Date: Sun, 9 Jan 2005 18:16:28 +0300

Jonathan,

Thanks for the correction.

Only my question was, why CPU time appears in the top 5 timed events
as 91% and the rest timed events are just 9%.
for your information, statspack snap elapsed time was 1 hr.
When I use response time formula, CPU Recursive show around 80% from
my statspack report. I tried to look for the SQL order by gets from my
statspack report. I just wanted to confirm, I am at the current place
or not to identified resource consuming queries.





On Sun, 9 Jan 2005 15:01:40 -0000, Jonathan Lewis
<jonathan@xxxxxxxxxxxxxxxxxx> wrote:
> 
> The question is almost meaningless.
> 
> Note first that the report is heading "Top 5 TIMED events"
> not "Top 5 WAIT events".
> 
> Now consider this - if you have used 4 CPU seconds
> in 1 elapsed second, what percentage of your CPU
> have you used ?  It depends on the number of CPUs
> 
> If you have waited for Disk I/O for 20 seconds in one
> elapsed second, how long (on average) has each
> user waited ? It depends on the number of concurrent
> users requesting disk I/O in that period.
> 
> It was (in some ways) a big mistake for Oracle to put
> the CPU usage exactly where they did; although it is
> a very important number to have available when you
> are looking at the wait events.
> 
> Ignore the CPU percentage from statspack. Factor
> in the number of CPUs, the number of concurrent
> active users, the elapsed time of the report.  And even
> then you haven't shown any reason why you might
> need to change anything.
> 
> Regards
> 
> Jonathan Lewis
> 
> http://www.jlcomp.demon.co.uk/faq/ind_faq.html
> The Co-operative Oracle Users' FAQ
> 
> http://www.jlcomp.demon.co.uk/seminar.html
> Public Appearances - schedule updated Dec 23rd 2004
> 
> 
> ----- Original Message -----
> From: "Jaffar_DBA" <sjaffarhussain@xxxxxxxxx>
> To: "Active DBA" <oracle-l@xxxxxxxxxxxxx>
> Sent: Sunday, January 09, 2005 1:48 PM
> Subject: CPU Time
> 
> Hello list,
> 
> If I have CPU time as my top most wait, what should I look for reducing it?
> Below are my top fives events and almost always, the top wait event is
> CPU Time .
> 
> Top 5 Timed Events
> ~~~~~~~~~~~~~~~~~~                                                     %
> Total
> Event                                               Waits    Time (s) Ela
> Time
> -------------------------------------------- ------------ ----------- --------
> CPU time
>   4,625    91.49
> db file sequential read                            95,317         140
> 2.76
> log file sync                                            47,051
> 118     2.33
> log file parallel write                                55,772
> 79     1.56
> SQL*Net more data to client                    46,977          69     1.36
> 
> Application background:
> 
> My application is an oline share trading application. We have only 3
> hours in the morning and 3 hours in the evening trading session.
> 
> --
> Best Regards,
> Jaffar, OCP DBA
> Banque Saudi Fransi
> Saudi Arabia
> --
> //www.freelists.org/webpage/oracle-l
> 
> --
> //www.freelists.org/webpage/oracle-l
> 


-- 
Best Regards,
Jaffar, OCP DBA
Banque Saudi Fransi
Saudi Arabia
--
//www.freelists.org/webpage/oracle-l

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