Re: Oracle CPU Time Used, vs CPU Time Available (CPU Capacity)

I once spent several days trying to figure out the information from the dba_hist* tables. I never really managed to get a calculation I was happy with, but you can start with dba_hist_sysmetric_summary, look at 'CPU Usage Per Sec' and 'Background CPU Usage Per Sec'. You get entries for each snapshot, so you can get a decent idea of what oracle sees. But I really have no good idea how accurate that is going to be. Especially with multiple db instances on a server.

On Thu, Sep 14, 2017 at 8:52 AM, Dominic Brooks <dombrooks_at_hotmail.com> wrote:

> Yep.
>
> Plus:
>
> 3) The connection pools are way over-sized – see real world performance
> group videos
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> *From: *Mladen Gogala <gogala.mladen_at_gmail.com>
> *Sent: *14 September 2017 12:49
> *To: *dombrooks_at_hotmail.com
> *Cc: *peter.fong_at_gmail.com; Chris Taylor
> <christopherdtaylor1994_at_gmail.com>; ORACLE-L <oracle-l_at_freelists.org>
> *Subject: *Re: Oracle CPU Time Used, vs CPU Time Available (CPU Capacity)
>
>
>
> On Thu, 14 Sep 2017 07:01:17 +0000
> Dominic Brooks <dombrooks_at_hotmail.com> wrote:
>
> > I have spent a lot of effort recently explaining that running at a
> sustained 95%
> > utilisation over a 1-2 hour period does not just mean that you’ve got an
> extra 5%
> > that you could be squeezing out...
>
> In case you described,you probably do not have that capacity. 95% of CPU
> usually means run queue and kernel overhead which will easily devour the
> remaining 5%. Such sustained consumption can mean one of two things:
> 1) You need a bigger box (or vbox).
> 2) There is a sub-optimal task running on the machine which needs to be
> optimized.
>
> --
> Mladen Gogala
> Oracle DBA
> Tel: (347) 321-1217
>
>
>

-- 
Andrew W. Kerber

'If at first you dont succeed, dont take up skydiving.'

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