Re: Physical Memory Fully Used and Swap is Not Used
- From: Andrew Kerber <andrew.kerber@xxxxxxxxx>
- To: hagan@xxxxxxx
- Date: Tue, 23 Jun 2009 08:30:19 -0500
Well, as a wild shot in the dark, your memory usage looks ok. What does
your disk IO time and CPU usage look like? If you feel safe in posting an
AWR report from the time you are noting slow response, we would be able to
tell a lot more..
On Tue, Jun 23, 2009 at 8:15 AM, Craig Hagan <hagan@xxxxxxx> wrote:
> ps on linux tells you the aggregate size of the process. Try adding
> up all of what you see and you'll quickly realize that it is a pack of lies
> when the sum is much much greater than physical memory. The trick is that
> linux is pretty good about sharing pages (copy on write/etc) between
> processes.
>
> As for main memory, you can start with "free" and look at
> what is available w/o caches.
>
> A few things: the original poster hasn't really given enough information
> which would help out quite a bit.
>
> 1) which version of redhat
>
> 2) 32bit or 64bit? if not 64bit, why not?
>
> 3) are hugepages being used for the sga? if not, why not? if so, how many
> are allocated? how many are in use? (cat /proc/meminfo to look)
>
> 4) what are the relevent sga/cache size settings for this instance?
>
> 5) has the op scoured metalink regarding that pmon error and/or openned an
> SR?
>
> -- craig
>
> On Tue, Jun 23, 2009 at 3:29 AM, Yechiel Adar <adar666@xxxxxxxxxxxx>wrote:
>
>> I think that ps that shows the memory usage of all processes in the
>> server is in order.
>>
>> Adar Yechiel
>> Rechovot, Israel
>>
>>
>>
>> Mudhalvan Moovarkku wrote:
>>
>> Mathias,
>>
>>
>>
>> Thanks for your mail.
>>
>>
>>
>> Yes I do understand. Now I have two clarifications.
>>
>>
>>
>> 1. Problem is at this point instead of using Swap My server
>> response time was very slow and PMON process failed with the message at
>> alert “PMON failed to acquire latch” and DB went down.
>>
>>
>>
>> 2. In 8.0.6 on Unix used only 7GB Memory but why in 10.2.0.4 on
>> Linux uses more than 16GB
>>
>>
>>
>> Regards
>>
>> Mudhalvan M.M
>>
>>
>> ------------------------------
>>
>> *From:* mathiasmag@xxxxxxxxx
>> [mailto:mathiasmag@xxxxxxxxx<mathiasmag@xxxxxxxxx>]
>> *On Behalf Of *Mathias Magnusson
>> *Sent:* Tuesday, June 23, 2009 3:15 PM
>> *To:* Mudhalvan Moovarkku
>> *Cc:* oracle-l@xxxxxxxxxxxxx
>> *Subject:* Re: Physical Memory Fully Used and Swap is Not Used
>>
>>
>>
>> Are you trying to tune or to understand memory? There is nothing here that
>> would indicate a problem. If you use all you memory and no swap, then that
>> would be optimal. It shows that your box is sized perfectly and you do not
>> ned to use swap. Using swap reduces performance (if we compare to having
>> enough memory and not needing swap).
>>
>>
>>
>> If on the other hand you motivation is to understand why these numbers
>> would be this way, then someone who has spent more time reading RDAs on
>> Linux would need to answer here. To me the numbers would indicate that you
>> have just barely reached the point where swap is starting to be used when
>> more memory is needed.
>>
>>
>> Mathias
>> http://mathiasmagnusson.com
>> http://blog.mathiasmagnusson.com
>> http://photo.mathiasmagnusson.com
>> http://oradbdev.mathiasmagnusson.com
>>
>> On Tue, Jun 23, 2009 at 7:41 AM, Mudhalvan Moovarkku <
>> moovarkku.mudhalvan@xxxxxxxxxxxxxxxx> wrote:
>>
>> Dear DBAs,
>>
>> We have recently migrated Oracle from 8.0.6 on HP-Unix to
>> 10.2.0.4 on Red Hat Linux
>>
>> Earlier the same application worked fine with 7GB RAM on HP-UNIX
>> on PA-RISC
>>
>> Upgraded system on IBM X 3850 with 16GB RAM but still we have
>> some performance issue.
>>
>> I knew there is some lagging because of Hardware Architecture but
>> it is too bad 7 GB to 16GB RAM but still have performance.
>>
>> Please look at data collected from RDA. Looking at this scenario
>> my physical memory is fullly used but Swap is not at all used.
>>
>> Total Physical Memory 16032 MiB
>>
>> Available Physical Memory 30 MiB
>>
>> Swap: Max Size 24575 MiB
>>
>> Swap: Available 24505 MiB
>>
>> Swap: In Use 70 MiB
>>
>> We know there is some performance issue in application. I would
>> like to make as much as possible from Database/Linux side tunning to provide
>> atlease peaceful performance. Can any body through some light on why the
>> swap is not at all used.
>>
>> Regards
>>
>> Mudhalvan M.M
>>
>>
>>
>>
>
>
> --
> .- ... . -.-. .-. . - -- . ... ... .- --. .
>
> Craig I. Hagan
> hagan(at)cih.com
>
> "Those who can make you believe absurdities can make you commit
> atrocities."
>
> Voltaire
>
>
--
Andrew W. Kerber
'If at first you dont succeed, dont take up skydiving.'
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