Re: cpu average load
- From: Martic Zoran <zoran_martic@xxxxxxxxx>
- To: Mladen Gogala <gogala@xxxxxxxxxxxxx>
- Date: Wed, 1 Dec 2004 05:52:01 -0800 (PST)
Mladen,
Thanks a lot.
I did not notice a big performance hit with using
timed_os_statistics=1 at all.
I am using it for a long time, and I even tested the
difference with or without timed_os_statistics.
This is why I am asking this.
Also collecting event 10046 level 8 is also not very
nice in some cases :)
I suppose Oracle is using the specific microaccounting
OS command (if available on the OS) to get the CPU
usage every second in my case.
The same will be if you are doing it with prstat -ma
for example every second on the OS level.
Just not sure how acurrate and fast is it?
I agree that you can use OS tools (GlancePlus is
great).
I am doing the same, even stupid ps or top that you
can run just at the start and stop of your monitoring
period will give you the overall CPU usage on the OS
level.
Then you got it on the Oracle level and compare it
from the OS. If the difference is not that huge great.
If it is then check queuing and other things/commands
like sar.
But, is it not easier if you just view v$sesstat and
got all CPU timings + v$session_event for all waits :)
Regards,
Zoran
--- Mladen Gogala <gogala@xxxxxxxxxxxxx> wrote:
>
> On 12/01/2004 04:41:48 AM, Martic Zoran wrote:
> >
>
> >
> > But, not sure that it is not possible to be
> covered
> > differently with timed_os_statistics parameter
> that is
> > giving you at least some OS timing statistics from
> v$
> > views.
> >
> > Is that reliable?
> > Did anybody was playing with this apart from me?
>
> I wasn't as oracle warns us, in the performance
> tuning manual, that
> collecting OS statistics is extremely expensive. In
> addition to that,
> Oracle RDBMS as an OS monitor is extremely expensive
> compared to top,
> sar, iostat, vmstat or GlancePlus (this is an
> excellent monitor).
> Typically, if oracle processes are spending too much
> time in kernel
> mode, there is a problem with the system health
> itself.
>
> --
> Mladen Gogala
> Oracle DBA
>
>
>
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