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The Dimensions of Service Exploring WLM’s Solution Space. NC CMG Tuesday 4 Nov 2003. Rich Olcott Schering-Plough Corp (now with IBM Global Services). Agenda. Elements of control theory Overview of WLM A strategic tool: the Goal Map The Attainment dimension: PI

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the dimensions of service exploring wlm s solution space

The Dimensions of ServiceExploring WLM’s Solution Space

NC CMG

Tuesday 4 Nov 2003

Rich Olcott

Schering-Plough Corp

(now with IBM Global Services)

agenda
Agenda
  • Elements of control theory
  • Overview of WLM
  • A strategic tool: the Goal Map
  • The Attainment dimension: PI
  • The Cost dimension: SU absorption
  • A tactical tool: the Actuals Map
  • Another tactical tool: the CR Map
control response curve
Control/Response Curve

Describes the relationship between what you do and what you get.

Generally depends on both the controlled system and its environment.

“If you can’t measure the response curve, you can’t manage the response.”

X

wlm meets its goals by
WLM meets its goals by…

I/O

  • DP for interrupts
  • (Add’l paths)

CPU access

  • Dispatch priority
  • (Add’l engine)

Server count

  • Enclaves (DDF, Web, stor’d proc)
  • (Batch inits)

Memory

  • Fencing
  • Swap in/out

… robbing Peter to pay Paul

workload management
Workload Management

Imp=2

Imp=2

Imp=2

Imp=3

Imp=3

Imp=3

Imp=3

Imp=2

Imp=3

3 dimensions of a goal

Importance

0

1 to 5

6

3 Dimensions of A Goal

Type

Value

SYSTEMS

Percentile

Response

Time

Velocity

Average

Response

Time

Discretionary

goal types
Goal Types
  • No goal (System, Discretionary)
  • Response Time
    • Average Response Time
      • Sum (RT) / (Transaction count)
    • Percentile Response Time
      • P% completed in less than target RT
  • Throughput
    • Velocity
      • Has nothing to do with speed (CPUsec / sec)
      • Has nothing to do with priority
      • Has nothing to do with Importance
what goes into velocity

100 * U

U + D

Vel =

Delayed

Using

What Goes into Velocity?

Task

Managed

Other

(Unk)

Idle

velocity and i o

100 * U

U + D

Vel =

I/O Operation

IOSQ

(UCB wait)

Pending

(path wait)

Disconnect

(latency)

Disconnect

(latency)

OW47667

OW47667,

IOPQ

PAV

IRD

Velocity and I/O

Task

Managed

Other

(Unk)

Idle

Delayed

Using

IOSQ

(UCB wait)

Pending

(path wait)

Disconnect

(latency)

Connect

(Xfer data)

velocity and cpu

Task

Managed

Other

(Unk)

Idle

Delayed

Using

100 * U

U + D

Vel =

Velocity and CPU

Estimated

“Using samples”

z/OS

OW55665

Measured CPU time

attained vs target
Attained vs Target

Target velocity

high velocities
“High” Velocities

SMFDUMP

LOGREC

NETVWLOG

RMFIIIBK

SYSLOG*

SYS1DUMP

WTRHSM

(Mean Etime = 15sec)

Bottom-feeders

prt vs art vs velocity

Umbrella, genl purpose DDF, etc, and outliers are politically visible

<10 completions per 20 minutes

All else

PRT vs ART vs Velocity

Velocity

PRT

ART

barred from rt eden
Barred from RT Eden

Long-running tasks, such as:

  • Conversational CICS
  • “Some” MQ-originated transactions
  • DDF with:
    • THREADS=ACTIVE in DB2 instance
    • RELEASE(DEALLOCATE) in DB2 plan
  • CATIA
  • CICS instance with no active RT goals
4 dimensions of a period
4 Dimensions of A Period

Importance

Period Id

0 1 2 3 4 5 6

CICPXN

TSO P1

TSO P2

SBAT

LBAT P1

LBAT P2

….

the goal map
The Goal Map
  • A one-page display of goal structure
  • Maps the strategic dimensions:
    • SC/Period Id - Importance
    • Goal type - Value(s)
  • Each SC period goal is plotted according to its Importance and its Workload
calculating pi
Calculating PI
  • General rules:
  • PI is a ratio that compares actual with target
  • PI is < 1.0 iff performance is better than target

Ave RT goal: PI=RTactual / RTtarget

Velocity goal: PI =Vtarget / Vactual

percentile response goal
Percentile Response Goal

A brilliant solution, but with pitfalls…

  • Most shops use percentile RT goals
  • Calculating any percentile is expensive
  • Solution: use buckets
    • Goal is “p% with response time < t ”
    • Define PI = (RT for p%)/(t)
    • Tally completions into buckets by RT
    • Calculate PI by interpolation between buckets
prt buckets the rtda
PRT Buckets - The RTDA

75%ile ~108% of target

==> PI = 1.08

percentile response goal26
Percentile Response Goal

A brilliant solution, but with pitfalls…

  • Most shops use percentile RT goals
  • Calculating any percentile is expensive
  • Solution: use buckets
    • Goal is “p% with response time < t ”
    • Define PI = (RT for p%)/(t)
    • Tally completions into buckets by RT
    • Calculate PI by interpolation between buckets
control response curve27
Control/Response Curve

WLM’s perspective on how the system behaves

“Controlled variable” = WLM’s Internal variables (SRM, etc.)

“Response” = PI

One curve per driver per SC period with a managed goal

Periodically re-estimated from current data

the cost of service
The Cost of Service

Service Units used =

C1 * (“TCB” CPU seconds)

+ C2 * (“SRB” CPU seconds)

+ C3 * (IO activity)

+ C4 * (CPU * memory)

C1 = CPU Coefficient * SRM constant

C2 = SRB coefficient * SRM constant

C3 = IOC coefficient

C4 = MSO Coefficient (should be 0.000)

... in WLM “Options” panel

the goal map in 3d
The Goal Map in 3D

SU Load

Importance

Workload

how to read a goal map
How to Read a Goal Map
  • WLM satisfies goals from left to right.
  • Within an importance level, WLM tends to maintain all workloads near the same PI value.
  • Within an importance level, the periods that draw the most resources are the ones with the most tasks and/or have the most aggressive goals.
smf data
T72(3), SCS section

Record per period per RMF recording interval

Goal type

Importance

Target value

Data for PI calc

RT %ile Buckets

T99(6)

Record per period per WLM policy adjustment intvl

Goal type

Importance

Target value

Local and Sysplex PI’s

SMF Data
lessons from smf data
Lessons from SMF Data
  • Generated only for in-use periods
  • Reports only the in-effect policy
  • In-effect classification rules are assumed, not reported
sdpds structure
SDPDS Structure

A standard ISPF ISPTLIB-style library

service goal tables
Service Goal Tables

* - For Periods 1-8: Disc (Y/N), Importance, SRM Duration, Velocity, %ile, Hr, Min, Sec

Policy name is either the base or one alternate.

lessons from the sdpds
Lessons from the SDPDS
  • An alternate policy is the base, plus one set of overrides.
    • Overrides apply to the base policy only.
  • Classification rules are global to an SD.
  • The SDPDS is the place to go for comprehensive knowledge of an SD.
  • Change mgmt and availability mgmt must be accomplished by PDS mgmt.
chg mgmt and the sdpds
Chg Mgmt and the SDPDS

Install

&SYSID.WLM.SDPDS.TRIAL

1 – Clone with WLM SAVE AS

3 – Clone with WLM SAVE AS

CDS

&SYSID.WLM.SDPDS.PROD

2 – Copy with ISPF =3.3

&SYSID.WLM.SDPDS.RESERVE

tactical dimensions
Tactical Dimensions
  • Service class/period identifier
  • Importance
  • Goal attainment (PI)
  • Cost (SU absorption rate)
  • Overall system load (total SU rate)
  • Time
one sc period in 3d
One SC Period in 3D

Cost

Time

Attainment

1.4 <= PI

SU’s used relative to other SC/pd’s in intrvl

0.6 < PI < 1.4

PI <= 0.6

15 min

reading an actuals map 1
Reading An Actuals Map - 1

Attainment dimension

SYSTEMS and DISC will always be

Expect high-importance lines to be

Expect patches of lower down, especially in a stressed system.

A lenient goal ==> persistent

An unmanageable goal ==> persistent

reading an actuals map 2
Reading An Actuals Map - 2

Cost dimension

Bar heights highlight the costliest SC/period in each interval.

“Tot SU Usage” is key to evaluating impact of a “heavy user” at a given time.

Watch for timing correlations between different lines.

cr maps
CR “Maps”
  • Need to locate cross-assignments, duplicates; identify missing items
  • WLM’s report
    • one report per subsystem
    • precedence structure within Subsystem
  • Alternative map structures
    • group work assigned to a Service Class
    • group work within a Report Class
    • line per workload, including descriptors
  • Spreadsheet format
    • slice and dice to taste
using the maps
Using the Maps
  • Strategic (especially the Goal Map)
    • Visualize effects of period elimination, overrides, Importance re-assignment
    • Training and negotiation tool
  • Tactical (especially the Actuals Map)
    • Goal tuning
    • Rule tuning
    • What-changed analysis
      • Use ISPF =3.13 to compare before-and-after Goal and CR report listings
additional goodies
Additional Goodies
  • SHOWWLM
    • REXX code to prepare Goal and CR maps
    • Called from TSO or batch
    • Reads SDPDS named at call time
  • SMF723
    • SAS code to prepare Actuals maps
    • Called from batch
    • Reads SMF data from DD-ref’d file

See http://home.mindspring.com/~rolcott/

server management

$SRMS001

TOR

Server Management

TOR

AOR

FOR

TOR

AOR

FOR

$SRMS002

TOR

AOR

FOR

http://www.schunk-associates.com/presentations/Share093/S2519pea.PDF

valedictory
Valedictory

Keep this message

close to your soul:

don’t mess with resources,

manage your goal.