Re: oracle memory usage + 11.2.0.1 + RHEL 5

If you are questioning why the swap space is filling up before memory has
been exhausted; then there are various Unix variants that write the
executable image to swap at the same time that the program is run.

My understanding is that this should result in a greater contiguity with
regards the running code and the image on disk and should lead to
performance improvements and the code is swapped out to disk.

I believe that it's an ELF thing. although there is no theoretical reason
why COFF based systems shouldn't implement the same functionality.


Regards

Dave

On Tue, Jul 27, 2010 at 5:58 PM, Stephens, Chris <Chris.Stephens@xxxxxxx>wrote:

>  I got a call from the system administrators yesterday about excessive
> swap usage on one of our database servers.  Swapping was not occurring but a
> significant percentage of swap was allocated.
>
>
>
> I recently created an 11.2.0.1 database on the server and configured the
> new memory_target and memory_max_target parameters to 2G.  The odd thing is
> that free –m showed a difference of 8GB in memory allocation between the
> database being up and down.
>
>
>
> Reading up on the new auto-memory magic a little indicates that the new
> memory management makes use of /dev/shm.
>
>
>
> Oddly (to me anyways) that is configured to 8gb:
>
>
>
> $ df -k /dev/shm
> Filesystem           1K-blocks      Used Available Use% Mounted on
> tmpfs                  8153816    625852   7527964   8% /dev/shm
>
>
>
>
>
> I’m struggling with how to explain this.
>
>
>
> That also got me thinking about the usefulness of an a script that
> accurately maps the memory usage of each oracle instance on a particular
> server.  In my short reading, it sounds like ‘ps’ isn’t very reliable since
> the memory reported per process also includes shared memory?  So, any
> thoughts on the most accurate way to break down the memory consumption of an
> instance and all user processes connected to it?
>
>
>
> Thanks in advance for any insight.
>
> CONFIDENTIALITY NOTICE:
> This message is intended for the use of the individual or entity to which
> it is addressed and may contain information that is privileged, confidential
> and exempt from disclosure under applicable law. If the reader of this
> message is not the intended recipient or the employee or agent responsible
> for delivering this message to the intended recipient, you are hereby
> notified that any dissemination, distribution or copying of this
> communication is strictly prohibited. If you have received this
> communication in error, please notify us immediately by email reply.
>
>
>

Other related posts: