Discussion:
IEFSCHAS - Using more CPU
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Peter Hunkeler
2017-09-13 07:03:39 UTC
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Not that I would think there is a problem, but in a problem situation, I saw IEFSCHAS using more CPU than normal. I never cared to understand what exactly IEFSCHAS does. Can anyone tell me?
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Peter Hunkeler

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Rob Scott
2017-09-13 09:53:45 UTC
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Peter

IEFSCHAS is the "scheduler address space".

One of its functions is to handle cross-system ENF notifications.

If the increased CPU consumption is down to an increase in cross-system ENF signals, then by far the most likely cause is an increase in GRS contention (as the other x-system ENF event codes are unlikely to be able to be generated *that* frequently).

Rob Scott

-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-***@LISTSERV.UA.EDU] On Behalf Of Peter Hunkeler
Sent: Wednesday, September 13, 2017 8:05 AM
To: IBM-***@LISTSERV.UA.EDU
Subject: IEFSCHAS - Using more CPU

Not that I would think there is a problem, but in a problem situation, I saw IEFSCHAS using more CPU than normal. I never cared to understand what exactly IEFSCHAS does. Can anyone tell me?



--
Peter Hunkeler

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Martin Packer
2017-09-13 10:03:55 UTC
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Sometimes I see SMF 30 for Master Scheduler AS showing very large amounts
of memory.

SMF 30 is extremely unreliable for memory anyway, so I'm not sure what to
make of that.

Cheers, Martin

Martin Packer,
zChampion, Principal Systems Investigator,
Worldwide Cloud & Systems Performance, IBM

+44-7802-245-584

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From: Rob Scott <***@ROCKETSOFTWARE.COM>
To: IBM-***@LISTSERV.UA.EDU
Date: 13/09/2017 10:55
Subject: Re: IEFSCHAS - Using more CPU
Sent by: IBM Mainframe Discussion List <IBM-***@LISTSERV.UA.EDU>



Peter



IEFSCHAS is the "scheduler address space".



One of its functions is to handle cross-system ENF notifications.



If the increased CPU consumption is down to an increase in cross-system
ENF signals, then by far the most likely cause is an increase in GRS
contention (as the other x-system ENF event codes are unlikely to be able
to be generated *that* frequently).



Rob Scott



-----Original Message-----

From: IBM Mainframe Discussion List [mailto:IBM-***@LISTSERV.UA.EDU] On
Behalf Of Peter Hunkeler

Sent: Wednesday, September 13, 2017 8:05 AM

To: IBM-***@LISTSERV.UA.EDU

Subject: IEFSCHAS - Using more CPU



Not that I would think there is a problem, but in a problem situation, I
saw IEFSCHAS using more CPU than normal. I never cared to understand what
exactly IEFSCHAS does. Can anyone tell me?







--

Peter Hunkeler



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Peter Hunkeler
2017-09-14 05:21:35 UTC
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Sometimes I see SMF 30 for Master Scheduler AS showing very large amounts of memory. >>SMF 30 is extremely unreliable for memory anyway, so I'm not sure what to make of that.
You confuse me, Martin. I was not asking about the Master Scheduler (*MASTER*) nor about memory usage. What did you meant to tell me?
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Peter Hunkeler


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Martin Packer
2017-09-14 08:19:20 UTC
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It's possible I got confused. So what is a Scheduler Address Space, as
opposed to the MASTER Scheduler Address Space?

Thanks, Martin

Martin Packer,
zChampion, Principal Systems Investigator,
Worldwide Cloud & Systems Performance, IBM

+44-7802-245-584

email: ***@uk.ibm.com

Twitter / Facebook IDs: MartinPacker

Blog:
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From: Peter Hunkeler <***@GMX.CH>
To: IBM-***@LISTSERV.UA.EDU
Date: 14/09/2017 06:22
Subject: AW: Re: IEFSCHAS - Using more CPU
Post by Martin Packer
Sometimes I see SMF 30 for Master Scheduler AS showing very large amounts
of memory. >>SMF 30 is extremely unreliable for memory anyway, so I'm not
sure what to make of that.

You confuse me, Martin. I was not asking about the Master Scheduler
(*MASTER*) nor about memory usage. What did you meant to tell me?
--
Peter Hunkeler


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Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU

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Peter Hunkeler
2017-09-14 10:54:45 UTC
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Post by Martin Packer
It's possible I got confused. So what is a Scheduler Address Space, as
opposed to the MASTER Scheduler Address Space?


Martin, the former's jobname is IEFSCHAS, the latter's is *MASTER*. Two different address spaces.
--
Peter Hunkeler



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Peter Hunkeler
2017-09-14 05:19:17 UTC
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Post by Rob Scott
IEFSCHAS is the "scheduler address space".
One of its functions is to handle cross-system ENF notifications.
Thanks. I knew it means "scheduling address space" but I was wondering what is being scheduled from there. So ENF signals are one part, you say. What else does it schedule? Just curious.


The correlation to GRS contention seems reasonable reason in our case. The GRS instance which is the "contention resolver" (can't remember how it is called right now) is using more CPU as well.
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Peter Hunkeler



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Rob Scott
2017-09-14 09:24:26 UTC
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I don't have access to any source materials, however it could be that IEFSCHAS only purpose in life is to manage cross-system ENF signals.

Message IEFE002I with reason "IEFSCHAS ADDRESS SPACE UNAVAILABLE" indicates that the following items are impacted :

(i) The system will not notify other systems in the sysplex of system events occurring on this system that are normally signalled to other systems.

(ii) The system will not notify ENF listeners on this system of system events occurring on other systems

Nothing else is listed as being affected by IEFSCHAS not being available.

Rob Scott

-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-***@LISTSERV.UA.EDU] On Behalf Of Peter Hunkeler
Sent: Thursday, September 14, 2017 6:20 AM
To: IBM-***@LISTSERV.UA.EDU
Subject: AW: Re: IEFSCHAS - Using more CPU
Post by Rob Scott
IEFSCHAS is the "scheduler address space".
One of its functions is to handle cross-system ENF notifications.
Thanks. I knew it means "scheduling address space" but I was wondering what is being scheduled from there. So ENF signals are one part, you say. What else does it schedule? Just curious.


The correlation to GRS contention seems reasonable reason in our case. The GRS instance which is the "contention resolver" (can't remember how it is called right now) is using more CPU as well.


--
Peter Hunkeler



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Peter Hunkeler
2017-09-14 10:54:27 UTC
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Thanks, Rob, much appreciated.

-- Peter Hunkeler

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