Re: CPU Time calculation in AWR Reports
- From: "LS Cheng" <exriscer@xxxxxxxxx>
- To: tanel.poder.003@xxxxxxx
- Date: Fri, 2 Nov 2007 11:47:56 +0100
I think the difference may be because v$sysstat is refreshed after a call is
completed but in SYS_TIME_MODEL_CPU it gets refreshed every 3 seconds
Thanks
--
LSC
On Nov 1, 2007 6:10 PM, Tanel Poder <tanel.poder.003@xxxxxxx> wrote:
> Well you can trace the awrrpt run...
>
> I suspect (but don't know for sure) that AWR uses DBA_HIST_SYS_TIME_MODEL
> for its CPU info... V$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$sysstat b
> 8 where
> 9 a.stat_name = 'DB CPU'
> 10 and b.name = 'CPU used by this session'
> 11 /
>
> TIME_MODEL_SECONDS SYSSTAT_SECONDS MISSING_SECONDS
> ------------------ --------------- ---------------
> 126.997282 4.6276 122.369682
>
>
> --
> Regards,
> Tanel Poder
> http://blog.tanelpoder.com
>
>
> > -----Original Message-----
> > From: oracle-l-bounce@xxxxxxxxxxxxx
> > [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Luis
> > Fernando Cerri
> > Sent: Thursday, November 01, 2007 23:20
> > To: oracle-l@xxxxxxxxxxxxx
> > Subject: CPU Time calculation in AWR Reports
> >
> > Hello, list.
> >
> > At Statspack age, 'CPU Time' value in section 'Top 5 Timed
> > Events' was calculated as the difference of 'CPU used by this
> > session' values between two snapshots:
> >
> > select 'CPU' , (e.value-b.value)/100 time
> > from stats$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';
> >
> >
>
> --
> //www.freelists.org/webpage/oracle-l
>
>
>
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