Oracle FAQ | Your Portal to the Oracle Knowledge Grid |
Home -> Community -> Usenet -> c.d.o.server -> Re: sga_max_size - pre-allocated at instance startup?
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.comReceived on Fri Mar 03 2006 - 21:21:40 CST