Re: oracle memory usage + 11.2.0.1 + RHEL 5
- From: amit bansal <amit.bansal82@xxxxxxxxx>
- To: big.dave.roberts@xxxxxxxxxxxxxx
- Date: Fri, 30 Jul 2010 10:27:30 +0530
Chris,
Is this linux? Give output of /proc/meminfo
I noticed this when we had allocated hugepages (rhel4 u8) and because of
incorrect ulimit setting it was not being used. As OS has already reserved
the memory for hugepages , database took rest memory and also consumed lot
of swap. I believe you too are facing same issue
Regards
Amit
http://askdba.org/weblog/
On Tue, Jul 27, 2010 at 10:44 PM, David Roberts <
big.dave.roberts@xxxxxxxxxxxxxx> wrote:
> 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.
>>
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