IMS V12 Performance Enhancements

Dave ViguersIMS Performance

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Performance is based on measurements and projections using standard IBM benchmarks in a controlled environment. The actual throughput or performance that any user will experience will vary depending upon many factors, including considerations such as the amount of multiprogramming in the user's job stream, the I/O configuration, the storage configuration, and the workload processed. Therefore, no assurance can be given that an individual user will achieve results similar to those stated here.

IBM IOD 2011

10/17/11

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10/17/11 19:36

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IBM IOD 2011

10/17/11

Prensenter name here.ppt

10/17/11 19:36

Performance related Items in V12

Internal instruction path optimization

Logging enhancements

DBCTL TCB switch reduction

Fast Path Secondary Index support

APPC and OTMA synchronous shared queues enhancement

OTMA ACEE reduction

Dynamic buffer pool capability for full function

TCP/IP support for MSC

FP 64 bit buffer manager enhancements

And more.....

Measurement Methodology

Setup and customize environment#CP's, IMS workload, Regions, etc.

Execute measurementRun workload until stable and gather data

Analyze resultsTypically IMSPA, APA and/or HIS

RepeatFurther tuning or adjustments

Be sure results are repeatable

Measurement Environment

IBM z10 and z196 processorsMultiple LPAR's

ICF's

8300 and 8700 DASD

ESCON and FICON channels

128 MB/sec OSA cards

z/OS V1R11

IMS V11 an IMS V12

Internal path optimization

Updated compilerTake advantage of new hardware instructions

Restructure some high usage modulesReduce cache misses

Remove or change expensive instructionsSometimes one instruction can make a difference

General review of many other processes

Base function results

Several types of workloadsFull function

Fast Path

SMQ

Data Sharing

All performed equal or better than V11Offset additional path of new function

Logging

What changed?OLDS and WADS now extended format

OLDS and SLDS Striping for more bandwidth

OLDS buffers above the barReal was already 64 bit

Virtual storage now 64 bit instead of ECSA

WADS channel program rewritePrimarily to benefit mirroring environment

Also benefits non-mirrored systems

OLDS Buffers

Buffers and control blocks moved from ECSA to 64 bit

ECSA savings should be slightly more than the buffer size time the number of buffersTest with 2516 buffers of 24K = 64MB reduction in ECSA

So 100 buffers would be about 2.5MB savings

And 5000 would be around 120MB savings

And so on

OLDS Striping

Can now allocate multiple stripesOLDS and SLDS

No longer constrained to a single device

Could help heavy BMP times

May help online also with heavy logger demand

Measured over 350 MB per second on DS8700Note: DS8700 achieved about 35% more bandwidth than DS8300

Striping Results

WADS enhancement

Channel program rewriteReduce impact on mirroring environmentsMetro and Global

May also help in non-mirrored systems

Response time may be lower

V11 and V10 enhancement alsoReduce I/O time impact if record not in cache

Added by APAR to V11 and V10

Requires OA33810 and DS8700 R6.1 microcode

DBCTL TCB Switch Reduction

AKA threadsafe

Application must be defined as Threadsafe

Must use CICS TS V4.2

Early measurements by HursleyMore than 20% cpu savings

IMS measurements in progress

Fast Path Secondary Index

DEDB's can now have indexes definedIMS will maintain integrity of updates

FP DEDB's generally use less cpu than FFBut many users require indexing thusCould not take advantage of DEDB's

Savings will depend upon may factorsHow many DB's could be converted

How much of the workload accesses those DB's

And on and on

But could be substantial

FP 64 bit buffer manager

If you really like using DBBF, DBFX, BSIZE and ECSA you may continue to do so.For us old timers that don't like change

V12 64 bit is enhanced to:Pre-extend pools rather than wait for full condition

Compress pools when demand decreases

Some ECSA still requiredFor control blocks

OTMA ACEE Reduction

Prior to V12Each client connected to IMS could potentially have the same users (ACEE's)

ACEE was created for each client

V12 now eliminates duplicatesOne ACEE per user regardless of # clients

Less storage usage

Fewer hash table synonymsLess cpu to search

Synchronous SQ Enhancement

IMS will use XCF instead of RRSSelected by AOS=X parameter

Applies to OTMA CM1 and synchronous APPCSync level none or confirmSyncpoint will still require RRS

Simplifies implementation

Improves performance

SMQ improvements

FE/BE with BE processing 100% OTMA SYNCLVL=NONE63% reduction in cpu

OTMA SYNCLVL=CONFIRM81% reduction

FE/BE both processingOTMA SYNCLVL=NONE27% reduction

Full Function Dynamic Buffer Pool

Dynamically change number and size of buffersUpdate Pool commandIncrease or decrease

OSAM or VSAM

Probably want to make any change when volume is lowHowever it can be done at any time

Might save an outage

OSAM impact much lower than VSAM

Some other Performance Enhancements

MSC can now use TCP/IP in addition to VTAM, CTC, and MTM

IMS Connect RACF userid caching

Additional pools support 64 bit real

Member OLC option to only process PSB

zIIP support for CQS

Logger and FP avoid storage movement

Summary

V12 should perform equal or better than V11

Some functions perform significantly betterSynchronous shared queues

FPSI

Logging capacity

DBCTL

MSC

Virtual Storage reduction

V12 Performance paper coming soon!

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IBM IOD 2011

10/18/11

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