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IFA. IFA. IFA. IFA. IFA. IFA. Introduction to zAAP (zSeries Application Assist Processor) Don Deese Computer Management Sciences, Inc . www.cpexpert.com. IFA. IFA. IFA. IFA. All trademarks are the property of their respective owners. Presentation Outline.

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IFA

IFA

IFA

IFA

IFA

IFA

Introduction to zAAP

(zSeries Application Assist Processor)

Don Deese

Computer Management Sciences, Inc.

www.cpexpert.com

IFA

IFA

IFA

IFA

All trademarks are the property of their respective owners.


Presentation Outline

  • Overview of zAAP (IFA) Processor

  • Benefits and requirements of zAAP

  • Description of how zAAP works

  • User controls for zAAP processing

  • Performance considerations with zAAP

  • Data available to measure zAAP performance

  • Conclusions and references

NOTE: zAAP operates only in a PR/SM environment. All references to “central processor” or “zAAP/IFA processor” should be taken to mean “logical central processor” and “logical zAAP/IFA processor”.


What is zAAP (IFA) Processor

  • “Special processor” available with z890, z990, z9.

  • Called either zAAP or IFA (Integrated Facility for Applications) depending on IBM document.

  • Runs only JAVA work (zAAP-eligible work) under control of JVM.

  • Similar to IFL (Integrated Facility for Linux).

  • Does not increase MSU rating of z890, z990, or z9.

  • Purchase and maintenance cost are significantly lower than with standard central processor.


Z990 Processor Units – sample definition

CP

CP

CP

CP

Central processors (CP)

PU

PU

PU

PU

PU

PU

PU

PU

SAP

SAP

spare

spare

ICF

IFL

IFA

Special processors

System Assist Processor

SAP

ICF

Internal Coupling Facility

Special processors

IFL

Integrated Facility for Linux

IFA

Integrated Facility for Applications

PU

Unused


Z890 Processor Units – sample definition

IFA

IFA

PU

PU

PU

PU

SAP

CP

CP

Special processors

Central processors (CP)

System Assist Processor

SAP

Integrated Facility for Applications

IFA


Benefits of zAAP Processors

  • Attractively priced ($125K USD per zAAP engine).

  • IBM zSeries software charges are unaffected (MSU rating is unchanged when zAAP is added).

  • Can run JAVA work on zAAP attached to z890 (zAAP runs at full speed, while z890 CPs can run at potentially much lower sub-capacity speed).

  • Sub-capacity IBM software charges could be reduced.

  • Significantly lower maintenance costs than standard CPs.

  • Up to one zAAP processor per central processor in a CPC.


Limitations of zAAP processors

  • Available only with z890 and z990 (and above)

  • Only one zAAP per purchased central processor

  • Cannot execute user instructions (other than under control of JVM)

  • Does not processes I/O interrupts

  • With z890/z990, zAAP inherits LPAR attributes from LPAR definition

  • Does not participate in IRD management and retains initial LPAR weight even if WLM changes LPAR weight

  • Does not support WLM soft-capping (meaningless since IFA is not reflected in defined capacity)


How does zAAP (IFA) work?

  • zAAP-eligible work must be processed in LPAR with one or more normal CPs

  • JVM decides whether JAVA work is zAAP-eligible.

  • JVM notifies z/OS dispatcher that zAAP-eligible work is ready to execute

  • zAAP-eligible work is dispatched to IFA (or to CP).

  • User specifications control whether zAAP-eligible work executes on IFA and on CP, or executes only on IFA.

  • User specifications control whether zAAP-eligible work executes in competition with normal “goal” work.



zAAP External Controls in IEAOPTxx

  • IFACROSSOVER

  • With z/OS V1R6, specifies whether zAAP-eligible work

    can “cross over” to run on CP as well as on IFA.

  • Meaning and importance changes with z/OS V1R7.

  • IFAHONORPRIORITY

  • Specifies whether zAAP-eligible work and other work

    will be dispatched to both CP and IFA based on WLM-

    assigned priority.

  • zAAP-eligible work will always be dispatched on IFA

    based on WLM-assigned priority.

  • If zAAP-eligible work runs on CP below DISC priority,

    zAAP-eligible work will be dispatched based on WLM-

    assigned priority for the zAAP-eligible work.


zAAP Controls with z/OS V1R6

IFACROSSOVER and IFAHONORPRIORITY

But see OA14131 (applies z/OS V1R7 changes)


zAAP Controls with z/OS V1R7

IFAHONORPRIORITY, AWM, and IFACROSSOVER

AWM = Alternate Wait State Management


Sample z/OS Dispatching

IFACROSSOVER=YES (with z/OS V1R6)

AWM decides IFA “needs help” (with z/OS V1R7)

IFAHONORPRIORITY=YES

SYSTEM DISPATCH QUEUE

IFA DISPATCH QUEUE

z/OS Dispatcher selects “zAAP-eligible #4” for dispatch, since it is the highest priority.

  • If IFA available, dispatch to IFA.

  • If IFA not available, dispatch to CP.


Sample z/OS Dispatching

IFACROSSOVER=YES

IFAHONORPRIORITY=NO

SYSTEM DISPATCH QUEUE

IFA DISPATCH QUEUE

  • If IFA available, z/OS Dispatcher selects “zAAP- eligible #4”for dispatch, since it is highest priority.

  • z/OS Dispatcher selects “zAAP-eligible #4” for dispatch on CP below DISC.

  • .


Sample z/OS Dispatching

IFACROSSOVER=NO

IFAHONORPRIORITY=NO

SYSTEM DISPATCH QUEUE

IFA DISPATCH QUEUE

  • If IFA available, z/OS Dispatcher selects “zAAP- eligible #4”for dispatch, since it is highest priority.

  • z/OS Dispatcher will select “zAAP-eligible #4” for dispatch on CP only if no IFA in LPAR.


zAAP Performance considerations

z/OS V1R6 and z890/z990

  • Large number of central processors versus zAAP processors defined to LPAR

  • High Goal Importance of zAAP-eligible work

  • Low Goal Importance of zAAP-eligible work

  • High CPU activity level of central processors

  • With z890/z990, LPAR definitions could conflict with

    LPAR definitions for other shared special processors

    in “Pool 2”. Problem solved with z9 109.

  • PR/SM Logical to Physical processor ratio


Performance consideration with zAAP, z/OS V1R6

IFACROSSOVER=YES

IFAHONORPRIORITY=YES

SYSTEM DISPATCH QUEUE

IFA DISPATCH QUEUE

z/OS Dispatcher selects “zAAP-eligible #4” for dispatch.

  • If IFA available, dispatch to IFA.

  • If IFA not available, dispatch to CP.

With large number of logical CPs, zAAP-eligible work will tend to be done by CPs, rather than by IFA.


Performance consideration with zAAP, z/OS V1R6

IFACROSSOVER=YES

IFAHONORPRIORITY=YES

SYSTEM DISPATCH QUEUE

IFA DISPATCH QUEUE

z/OS Dispatcher selects “zAAP-eligible #4” for dispatch.

  • If IFA available, dispatch to IFA.

  • If IFA not available, dispatch to CP.

With high Goal Importance, zAAP-eligible work will tend to be done by CPs, rather than by IFA.


Performance consideration with zAAP, z/OS V1R6

IFACROSSOVER=YES

IFAHONORPRIORITY=YES

SYSTEM DISPATCH QUEUE

IFA DISPATCH QUEUE

z/OS Dispatcher selects “zAAP-eligible #4” for dispatch.

  • If IFA available, dispatch to IFA.

  • If IFA not available, dispatch to CP.

With low Goal Importance, zAAP-eligible work will tend to be done only by IFAs, which could imply that more zAAP processors are needed than expected.


Performance consideration with zAAP, z/OS V1R6

IFACROSSOVER=NO

IFAHONORPRIORITY=not applicable

SYSTEM DISPATCH QUEUE

IFA DISPATCH QUEUE

  • If IFA available, z/OS Dispatcher on IFA selects “zAAP- eligible #4”for dispatch.

  • z/OS Dispatcher on CP selects “zAAP-eligible #4” for dispatch only after “DISCR, not zAAP #1” dispatched.

If small number of IFAs defined to LPAR, zAAP-eligible work will tend to be delayed waiting on IFA.


CP

CP

CP

CP

Central processors (CP)

Performance consideration with zAAP on z890/z990

LPAR Definitions

ICF

IFL

IFA

Special processors (SP)

Dedicated

Before IFA

LCP = Logical Central Processor

LSP = Logical Special Processor

After IFA (Example only. SYSE cannot really have over 100% as only 1 IFA assigned to SYSE.)


CP

CP

CP

CP

Central processors (CP)

Performance consideration with zAAP on z890/z990

LPAR Definitions

ICF

IFL

IFA

Special processors (SP)

Dedicated

This situation really is no different than when adding any LPAR (except the zAAP

part is inherited from the central processor LPAR definition). You must carefully

review your weights and resulting shares considering LPARs with zAAPs.


CP

CP

CP

CP

Central processors (CP)

Performance consideration with zAAP on z890/z990

LPAR Definitions

ICF

IFL

IFA

IFA

Special processors (SP)

Dedicated


CP

CP

CP

CP

Central processors (CP)

Performance consideration with zAAP on z890/z990

LPAR Definitions

ICF

IFL

IFA

IFA

Special processors (SP)

Dedicated

Logical to Physical ratio - 12:3 (4:1)

IFL & IFA share comes from same pool

Unused IFL capacity can be used for IFA



Conclusions

  • zAAP offering appears to be an excellent way to obtain

    significantly increased processor capacity at a very

    attractive price.

  • Sufficient zAAP-eligible work must exist.

  • PR/SM definitions must be carefully reviewed (most problems solved with z9 109).

  • Service class Performance Goals and Goal Importance must be carefully considered.

  • IBM has provided sufficient RMF data for analysts to determine IFA processor capacity requirements and performance problems.

  • OW14131 and OW13953 solve many problems with z/OS V1R6.


References

  • GM13-0624 – Introducing the new zSeries Application Assist Processor

  • SG24-6310: IBM zSeries 890 Technical Introduction

  • SG24-6947: IBM zSeries 990 Technical Guide

  • SG24-6669: IBM z9 109 Technical Introduction

  • SG24-6386: zSeries Application Assist Processor (zAAP) Implementation

  • SB10-7036-03: zSeries 890 and 990 Processor Resource/Systems Manager Planning Guide

  • SG24-5922: z/OS Intelligent Resource Director

  • z/OS MVS Planning: Workload Management (z/OS V1R6 and z/OS V1R7)

  • MVS Initialization and Tuning Reference (z/OS V1R6 and z/OS V1R7)

  • z/OS Performance: Capacity Planning Considerations for zAAP White Paper

  • z990 and z890 zAAP - What it Can Do for You SHARE - Summer, 2004 MVS SCP Project Session: 2825, Kathy Walsh (IBM Washington Systems Center, Advanced Technical Support)


References

  • IBM White Paper (WP100489) Mission: zAAP your costs, Running Websphere and Java on the zSeries Application Assist Processor (updated)

  • IBM White Paper (WP100417) z/OS Performance: Capacity Planning Considerations for zAAP Processors

  • IBM EXPO 2005, Session P06 z/OS Performance "HOT"Topics, Kathy Walsh (IBM Washington Systems Center, Advanced Technical Support)

  • IBM EXPO 2005, Session P25 Everything zAAP, Kathy Walsh (IBM Washington Systems Center, Advanced Technical Support)

  • APAR 0A14131 and APAR 0A13953

  • http://www-1.ibm.com/servers/eserver/zseries/zaap/gettingstarted/


IFA

IFA

IFA

IFA

IFA

IFA

Introduction to zAAP

(zSeries Application Assist Processor)

Don Deese

Computer Management Sciences, Inc.

www.cpexpert.com

IFA

IFA

IFA

IFA

All trademarks are the property of their respective owners.


z890 Sub-capacity MSU rating

(28 capacity levels)

zAAP processor runs at full speed

Regardless of capacity rating!


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