Re: SIEBEL PERFORMANCE RBO to CBO
- From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 5 Feb 2007 07:33:12 -0000
Idle thought about HP-UX being the only case
where you see CURSOR: PIN S WAIT ON X
I believe the HP chip does not have a compare and
swap operation - which Oracle uses for sharable read
latches on most platforms. I would guess that the
mutex mechanism uses the same chip feature.
Presumably the CAS emulation that Oracle does
on HP-UX works okay for sharable latches, but
has a greater impact on the visibility of mutex
operations.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
Author: Cost Based Oracle: Fundamentals
http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html
The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html
----- Original Message ----- >
From: "Milen Kulev" <makulev@xxxxxxx>
Subject: RE: 10Gr2 and Library Cache Lock Waits
Date: Sun, 4 Feb 2007 12:13:49 +0100
Ian,
What waits events (from v$session_wait) do you get ?
If it is "CURSOR: PIN S WAIT ON X" you can try
_kks_use_mutex_pin = FALSE.
I have several databases , that are running since years well, but after 10g
upgrade
I have got many "CURSOR: PIN S WAIT ON X".
Perhaps it is a coinsidence, but all the databases that are experiencing this
problem are
Runnung on HPUX. Perhaps this problem has something to do with mutexes
implementation
On HPUX.
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