Re: Question about hugepages, shared memory, and /dev/shm....

By the way my customer DBA was removing these JOX files manually using rm
in Solaris and he had to reboot the instance because whent hose files are
removed when the instance is online all java calls in the database failed
with core dump so dont try to remove them manually!




On Wed, Apr 16, 2014 at 7:38 PM, Ls Cheng <exriscer@xxxxxxxxx> wrote:

> Hi
>
> I have seen those files in Solaris but in /tmp. It wass generated by JIT,
> Java In Time Compiler in my case, not sure if it applies in your case.
> Seems like it can be PL/SQL native compiled as well, since your are using
> EBS it might be the case? It has nothing to do with AMM or ASMM
>
> But look these notes
>
> /dev/shm Filled Up With Files In Format JOXSHM_EXT_xxx_SID_xxx (Doc ID
> 752899.1)
>
> Stale Native Code Files Are Being Cached with File Names Such as:
> JOXSHM_EXT*, PESHM_EXT*, PESLD* or SHMDJOXSHM_EXT* (Doc ID 1120143.1)
> Ora-7445 [Ioc_pin_shared_executable_object()] (Doc ID 1316906.1)
>
> Regards
>
> On Wed, Apr 16, 2014 at 5:47 PM, Mark Bobak <Mark.Bobak@xxxxxxxxxxxx>wrote:
>
>>  Hi All,
>>
>>  So, I thought I really understood this stuff, but I’m a little baffled
>> here, and I wonder if anyone can offer me a clue?
>>
>>  Here’s what I (think I) know:
>> 1.)  AMM (setting memory_target) is *not* compatible with a hugepages
>> configuration.  Any attempt to use hugepages will lock out the memory
>> allocated to hugepages and AMM will only use non-hugepage memory
>> allocations, the effect of which would be like removing the huge page
>> allocated memory from the system.
>> 2.)  ASMM (setting sga_target and pga_aggregate_target) and MMM (manually
>> setting db_cache_size and pool sizes) *are* compatible with a hugepages
>> configuration, and for any non-trivially sized SGA, hugepages is strongly
>> recommended.
>> 3.)  If hugepages are *not* configured, and AMM is used, memory segments
>> will be mapped in /dev/shm.
>> 4.)  If hugepages *are* used, no memory segments will be visible in
>> /dev/shm.
>>
>>  So, that’s what I think is true about memory configuration and
>> hugepages configuration.
>>
>>  That seems to be consistent throughout our environment, which mostly
>> has ASMM or MMM and hugepages configuration.
>>
>>  However, and this is where my confusion comes in, we have several eBS
>> environments, which seem to have a valid and active hugepages
>> configuration, are using ASMM (not AMM), and *still* I can see memory
>> segments allocated in /dev/shm??  Any idea how this is possible?
>>
>>  Here’s an example from our preprod environment:
>>  (Content was too long for Oracle-L, so here’s a paste bin URL)
>>
>>  http://pastebin.com/7w2V2jEa
>>
>>   So, I’m a little baffled here.  I thought these were mutually
>> exclusive features.
>>
>>
>>  Note also that the timestamps on the /dev/shm segments is *after*
>> instance startup time, so, I don’t think these are “orphan” memory
>> segments….
>>
>>
>>  Anyone out there can clue me in?
>>
>>
>>  Thanks,
>>
>>
>>  -Mark
>>
>
>

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