RE: shared server configuration

From: Yong Huang <yong321_at_yahoo.com>
Date: Thu, 21 Oct 2010 09:47:28 -0700 (PDT)
Message-ID: <664183.38848.qm_at_web80604.mail.mud.yahoo.com>



Dick,

I have the impression of higher CPU usage when we changed from dedicated to shared server config a few years ago running 9i. I don't remember if we had stats to prove that, and it's quite possible these are just bugs in 9i, such as "Bug 5574166: CPU USAGE AS DOUBLE IN SHARED SERVER MODE".

When the shared server is executing the SQL on behalf of a session, the session stays on the shared server (even when there's no traffic on Oracle Net). It only switches off to the dispatcher when the SQL execution is finished. Next time when it needs to execute a SQL, it will again be attached to a (possibly different) shared server. I only guess without proof that this switching on and off takes significant CPU.

You're absolutely right that the shared pool size should be increased.

Yong Huang

  • On Thu, 10/21/10, Goulet, Richard <Richard.Goulet_at_parexel.com> wrote:

> Yong,
>
> I regret to say that I have not seen
> shared server sessions
> consume more cpu that dedicated. The reason is that
> the user places
> their sql into the request queue for processing and then
> retrieves their
> results from the result queue, both of which live in the
> shared pool.
> Which is why when switching modes you should increase
> shared pool, and
> consequently the session does not really switch contexts
> from the
> dispatcher to the shared server.
>
>
> Dick Goulet
> Senior Oracle DBA
      

--
http://www.freelists.org/webpage/oracle-l
Received on Thu Oct 21 2010 - 11:47:28 CDT

Original text of this message