RE: CPU Time calculation in AWR Reports

From: Tanel Poder <tanel.poder.003_at_mail.ee>
Date: Fri, 02 Nov 2007 01:10:30 +0800
Message-id: <036601c81caa$1b270820$3201a8c0@windows01>

Well you can trace the awrrpt run...

I suspect (but don't know for sure) that AWR uses DBA_HIST_SYS_TIME_MODEL for its CPU info... V$SYS_TIME_MODEL CPU values can differ from V$SYSSTAT ones...

SQL> select

  2     a.value/1000000 time_model_seconds,
  3     b.value/10000   sysstat_seconds,
  4     a.value/1000000 - b.value/10000 missing_seconds
  5  from
  6     v$sys_time_model a,
  7     v$sysstat b
  8  where
  9     a.stat_name = 'DB CPU'

 10 and b.name = 'CPU used by this session'  11 /

TIME_MODEL_SECONDS SYSSTAT_SECONDS MISSING_SECONDS

------------------ --------------- ---------------
        126.997282          4.6276      122.369682

--
Regards,
Tanel Poder
http://blog.tanelpoder.com
 



> -----Original Message-----

> From: oracle-l-bounce_at_freelists.org 

> [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Luis 

> Fernando Cerri

> Sent: Thursday, November 01, 2007 23:20

> To: oracle-l_at_freelists.org

> Subject: CPU Time calculation in AWR Reports

> 

> Hello, list.

> 

> At Statspack age, 'CPU Time' value in section 'Top 5 Timed 

> Events' was calculated as the difference of 'CPU used by this 

> session' values between two snapshots:

> 

>                        select 'CPU' , (e.value-b.value)/100 time

>                          from stats$sysstat b, stats$sysstat e

>                         where e.snap_id         = :v_eid

>                           and b.snap_id         = :v_bid

>                           and e.name            = 'CPU used 

> by this session'

>                           and b.name            = 'CPU used 

> by this session';

> 

> 


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Received on Thu Nov 01 2007 - 12:10:30 CDT