Re: Hugepages usage

You are correct. It is the AMM that is preventing the use of huge pages. You will need to remove that and set SGA and PGA separately to use huge pages. A 30 GB SGA should be fine with 32 GB huge pages.

Keith

> On Feb 10, 2020, at 5:43 PM, Ram K <lambu999_at_gmail.com> wrote:
>
> Thanks Keith and Andrew.
>
> SQL> sho parameter use_large_p
>
> NAME TYPE VALUE
> ------------------------------------ -------------------------------- ------------------------------
> use_large_pages string TRUE
> SQL>
> SQL>
> SQL> sho parameter memory
>
> NAME TYPE VALUE
> ------------------------------------ -------------------------------- ------------------------------
> ...
> memory_max_target big integer 32G
> memory_target big integer 32G
> ...
> SQL>
> SQL>
> SQL> sho parameter sga
>
> NAME TYPE VALUE
> ------------------------------------ -------------------------------- ------------------------------
> lock_sga boolean FALSE
> pre_page_sga boolean TRUE
> sga_max_size big integer 30G
> sga_target big integer 30G
> unified_audit_sga_queue_size integer 1048576
> SQL>
>
> -----------------------------------------------------------------------------------------------------------------------------
>
> Given that AMM is set, can I assume that ASMM is not enabled and the 'sga' parameters (sga_max_size and sga_target) are for the high values only?
>
> Once the hugepages is enabled at the OS level and if I try to restart with the above AMM settings can I assume the restart will not happen because AMM and huge pages are not compatible?
>
> PS. the server has 64Gb memory.
>
>
> On Mon, Feb 10, 2020 at 5:24 PM Keith Moore <keithmooredba_at_gmail.com <mailto:keithmooredba_at_gmail.com>> wrote:
> How large is you SGA? Also, what setting for USE_LARGE_PAGES parameter?
>
> Set USE_LARGE_PAGES to only and see if the database will start. You may not have enough huge pages (24 GB).
>
> Keith
>

>> On Feb 10, 2020, at 5:20 PM, Ram K <lambu999_at_gmail.com <mailto:lambu999_at_gmail.com>> wrote:
>> 
>> 
>> Thanks Andrew. What is 'Anonymous Hugepages'. Is it the same as Transparent Huge Pages that Oracle recommends to disable <https://docs.oracle.com/en/database/oracle/oracle-database/19/unxar/administering-oracle-database-on-linux.html#GUID-02E9147D-D565-4AF8-B12A-8E6E9F74BEEA>? 
>> 
>> 
>> On Mon, Feb 10, 2020 at 5:05 PM Andrew Kerber <andrew.kerber_at_gmail.com <mailto:andrew.kerber_at_gmail.com>> wrote:
>> You are correct, if the DB is up and running and all the huge pages are free as shown here, they are not being used. Anonymous hugepages should be disabled for all oracle servers. 
>> 
>> Sent from my iPad
>> 
>> > On Feb 10, 2020, at 17:03, Ram K <lambu999_at_gmail.com <mailto:lambu999_at_gmail.com>> wrote:
>> > 
>> > 
>> > 
>> > Hi,
>> > 
>> > I came across this setting in a Linux server running oracle 12. 
>> >   
>> > grep Huge /proc/meminfo
>> > AnonHugePages:     43008 kB
>> > HugePages_Total:   12288
>> > HugePages_Free:    12288
>> > HugePages_Rsvd:        0
>> > HugePages_Surp:        0
>> > Hugepagesize:       2048 kB
>> > 
>> > Does this mean that hugepages are not being used since all the Hugepages are free? 
>> > How can I find out if hugepages were ever used, to make sure I am not looking at an isolated time period when it is not being used. 
>> > 
>> > -- 
>> > Thanks,
>> > Ram.
>> 
>> 
>> -- 
>> Thanks,
>> Ram.

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