Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> c.d.o.server -> Re: sga_max_size - pre-allocated at instance startup?

Re: sga_max_size - pre-allocated at instance startup?

From: Mladen Gogala <gogala_at_sbcglobal.net>
Date: Sat, 04 Mar 2006 03:21:40 GMT
Message-Id: <pan.2006.03.04.03.21.40.53245@sbcglobal.net>


On Fri, 03 Mar 2006 15:26:40 -0800, Joel Garry wrote:

> Solaris and hp-ux have always implemented shared memory different from
> each other in my experience (back to SunOS 1.2 and hp-ux 9). Just
> because Posix has a service definition and ipc* have the same syntax
> doesn't mean things work the same, although they are getting closer in
> more recent Oracle.

Solaris has a perversion called "intimate shared memory, which allows processes to share page table as well as the page contents. From Oracle 7.3 all the way to 8i there was a parameter called "use_intimately_shared_memory", which was supposed to be set to true on Solaris. That parameter would enable Oracle to use XXX-shared memory and gain some performance. Another thing with which many vendors were toying was the post-wait pseudo device, which was faster then the semaphore operations. It was originally developed by SGI but I've seen it on AIX and Solaris as well. I do believe that Oracle was using classic shmget,shmat and similar calls wherever available and would switch to specialized libraries, based on parameters. Of course, I never worked for Oracle and I've never seen the source code, so I don't really know.

-- 
http://www.mgogala.com
Received on Fri Mar 03 2006 - 21:21:40 CST

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US