Re: CPU Time calculation in AWR Reports

Thanks for your valuable and precise suggestion, Tanel.

In a nutshell, this is what AWR does:

   select 'CPU' , (e.value-b.value)/1000000 time

     from dba_hist_sys_time_model b, dba_hist_sys_time_model e
    where e.snap_id         = :v_eid
      and b.snap_id         = :v_bid
      and e.stat_name       = 'DB CPU'
      and b.stat_name       = 'DB CPU';

Best regards,
Cerri

2007/11/1, Tanel Poder <tanel.poder.003_at_mail.ee>:
> 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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