ST02 : Used Extended memory calculation

[Former Member]

Hello.

Does anybody know how the value shown in ST02 Extended Memory Used is calculated?

We see a large difference between this value and the sum of memory shown in SM04 , so we guess that something else contributes to increase the value of used extended memory, but cannot find what...

Thanks a lot, kind regards,

Dino

[former_member185954]

Hello Dino,

What is the difference , can you post some values.

it would be great if you can post screenshots of ST02 and SM04

Regards,

Siddhesh

[Former Member]

Hi.

Thanks for your reply, but I cannot find how to post attachments here. I sent the screenshots via mail.

Actually, Currently used Extended memory in ST02 shows 2.994.176 KB , while the sum of memory used in SM04 is 1.886.582.480 bytes, there is more than 1 GB difference....

Kind regards,

Dino

Edited by: Dino Dose on Sep 17, 2008 9:12 AM

[former_member185954]

Hello,

The difference could be due to internal fragmentation of your Extended memory.

The programs would generally request blocks of memory

ST02 counts memory blocks allocated and SM04 calculates actual memory used by user sessions.

I searched for Extended Memory fragmentation and found the following SAP Note:

SAP Note Number: 127871 - Apparent differences of memory use display

Regards,

Siddhesh

[Former Member]

Hello.

Looking at the ST02->Detail Analyis Menu -> SAP Memory->Mode List

and summing up the EM usage of all users modes, the total is compatible with the ST02 Current Extended Memory used. Just adding to this value em/global_area_MB + abap/shared_objects_size_MB , you will get the same values.

So the SM04 display cannot be really trusted regarding the memory usage.

Thanks a lot for your help.

Dino

[former_member185954]

Extended memory is used by switching pointers so its allocated non-sequentially in blocks.

the mode list gives u the list of blocks.

The SM04 memory allocation 'might' be calculating memory sums using the 'actual' memory used in these allocated memory blocks.

for e.g.

block size is 1MB , however actual used within block is just 500KB so I can imagine there would always be a difference between EM size in ST02 and allocation in SM04.

Regards,

Siddhesh

[Former Member]

Hi Dino,

Please note that the extend memory used which we see in ST02 for any instance is a cumulative value. Once we restart the server it comes down to 0.

Thank you,

Tilak