It's not a huge performance issue but it should definitely be cleaned up.  I'll 
submit an RFE and Share requirement.  We'll see who wants to jump on the 
bandwagon.

Thanks again.

Robert Crawford
Mainframe Management
United Services Automobile Association
(210) 913-3822

« Des clochards comme nous, bébé nous sommes nés pour courir » - Voltaire
Please send requests to mainframe management through our front door at  
go/mfmfrontdoor

-----Original Message-----
From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of 
Seymour J Metz
Sent: Thursday, June 3, 2021 9:14 AM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: EXTERNAL: Re: Why Would COPYSRVH Cause a 1M Page Demtion [Internal]

IBM takes formal customer requests into account. If you need it, then it is in 
your best interest to submit a formal requirements and to ask others to endorse 
it, whether that be a direct RFE or a SHARE requirement. It's really a win-win 
proposition; it helps you and it helps IBM.


--
Shmuel (Seymour J.) Metz
https://urldefense.com/v3/__http://mason.gmu.edu/*smetz3__;fg!!GryZGb6B1VCs0SfC!QMUuiuZCVrO-GbcjmeQ6mA3kR9wvJYFrD1ahHbKd0G6UpmX7n61Ed8oSwKxLkEsS8xY$
 

________________________________________
From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of 
Crawford, Robert C. [000001feadb2c2d2-dmarc-requ...@listserv.ua.edu]
Sent: Thursday, June 3, 2021 9:12 AM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: EXTERNAL: Re: Why Would COPYSRVH Cause a 1M Page Demtion [Internal]

Jim,

Thank you for the explanation.  It is WAD (working as designed).

Do I need to submit a formal requirement or is being on the list sufficient?

Thanks again.

Robert Crawford
Mainframe Management
United Services Automobile Association
(210) 913-3822

« Des clochards comme nous, bébé nous sommes nés pour courir » - Voltaire 
Please send requests to mainframe management through our front door at  
go/mfmfrontdoor

-----Original Message-----
From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Jim 
Mulder
Sent: Wednesday, June 2, 2021 9:53 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: EXTERNAL: Re: Why Would COPYSRVH Cause a 1M Page Demtion [Internal]

Here's what happened:

Apar: OA41307
Abstract: FORK FAILURE WHEN ADDRESS SPACE OWNS 1MEG PAGES Closed Date: 13/02/23 
RSM support for FORK copies high virtual memory objects from the parent address 
space to the child as part of duplicating the parent process' address space. 
However, the request currently fails if the parent process owns high virtual 
that consists of one megabyte pages.

PROBLEM CONCLUSION:

TEMPORARY FIX:
*********
* HIPER *
*********

COMMENTS:
All pageable 1M pages in the parent address space will be demoted to 4k pages 
and copied into the child address space.


  The easiest and safest solution for the APAR was to simply demote the source 
1MB pages so the the existing code could then handle them.  Over the years, RSM 
has changed other functions to reduce the number of cases where demotion is 
done. For example, z/OS 2.2 avoids demotion when possible for PGSER FIX. and 
z/OS 2.3 tries to avoid demotion when
IARV64 PAGEFIX  fixes a portion of a 1MB page.  Unfortunately, ForkCopy slipped 
through the cracks.  As a result of your question, it is being added to the 
list of things to look at for a future release.

Jim Mulder z/OS Diagnosis, Design, Development, Test  IBM Corp.
Poughkeepsie NY


"IBM Mainframe Discussion List" <IBM-MAIN@LISTSERV.UA.EDU> wrote on
06/02/2021 04:49:14 PM:

> From: "Crawford, Robert C."
<000001feadb2c2d2-dmarc-requ...@listserv.ua.edu>
> To: IBM-MAIN@LISTSERV.UA.EDU
> Date: 06/02/2021 10:35 PM
> Subject: Re: EXTERNAL: Re: Why Would COPYSRVH Cause a 1M Page Demtion 
> [Internal] Sent by: "IBM Mainframe Discussion List"
> <IBM-MAIN@LISTSERV.UA.EDU>
>
> Here is the full trace.  I'll gladly accept any help in interpreting.
>
> Sorry about the bad formatting.
>
> SYS5      SGTDEM64  00000063  12:44:53.270019  Demote 1M 64 bit page
>      FUNC1... COPYSRVH          High Virtual Copy Service
>      JOBN1... ZUMCCMG1 ASID1... 0215     PLOCKS.. 8800C001 CPU.....
> 0006
>      JOBN2... ZUMCCMG3 ASID2... 022D     RLOCKS.. 8800C001 RLOCKDET
> 0800     ADASID.. 0215     XMASID.. 022D     CMASID.. 0000
> STASID.. 0000
>      KEY..... 0036     ADDR.... 035E1008 ALET.... 00000000
>      70207520 C710
>      KEY..... 009A     ADDR.... 035E22B0 ALET.... 00000000
>      035E22F8 00000000 00000000 00000000 00000000 00000000 01000000
> 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 00000000 00000000 00000000
>      00000000
>      KEY..... 009B     ADDR.... 035E22F8 ALET.... 00000000
>      00000001 01000003 7FF74D38 04134B00 0000003B E5398D00 00000000
> 00000000 00000000 00000000 00000050 1A000000 00000000 00000000
> 00000000 00000000 00000000
>      00000000
>
>
> Robert Crawford
> Mainframe Management
> United Services Automobile Association
> (210) 913-3822




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