Advanced Techniques To Measure The Memory Component

Today’s Agenda:
1) Why Do We Need To Measure The Memory Component?
2) Machine Pool Memory / Best Practice Guidelines
3) Techniques To Measure The Memory Component
a) Understanding Your Current Environment
b) Historical Analysis
c) Performance Adjuster - Are You Set Up Efficiently?
d) Advanced Memory Analysis / Techniques
4) New Product Functionality
5) Q&A

Why Do We Need To Measure The Memory Component?
To answer that, let’s take a step back and understand some basic
memory terminology
I get asked this question all the time – What is a fault?
Here is a great definition one of my mentors gave me years ago:
A fault occurs when a virtual address is referenced, but it is not in main storage.
When a fault occurs, a job will stop dead in its tracks and wait for an I/O, and by
definition, it is a synchronous I/O.

Why Do We Need To Measure The Memory Component?
Why is that important?
Excessive faulting on your system can cause your system / applications
to slow down
A Real life example with my Mom’s new PC

Why Do We Need To Measure The Memory Component?
So it slows down a bit…why is that important?
Bad response for your internal / external customers
Nightly Batch Processing Takes Longer To Run
(Jobs are taking longer to complete)

Private Pools - Reminder Of How They Work
Private Pools – areas of memory set aside to be used for specific processing
A Good Example: 1 Gig of memory just for Websphere
Remember: Private pool memory will stay isolated from shared pool memory…if that
processing is idle, that memory is not being used for other resources that may need it…
Is that bad? It Depends. If you have a lot of memory, No Problem
If you are robbing peter to pay paul, then it’s a problem

Private Pools - Reminder Of How They Work
Private Pool Example:

Shared Pools - Reminder Of How They Work
Shared Pools – Shared pools are either special or general; the Machine pool and
Base pool are considered special shared pools, and all other shared pools are
considered general shared pools
General shared pools are pools of main storage that multiple subsystems can use at the
same time.
*INTERACT is the interactive storage pool used for interactive jobs.
*SPOOL is the storage pool used for spool writers.
*SHRPOOL1 through *SHRPOOL60 are storage pools that you can use for your own
use.
NOTE: Set up via the WRKSHRPOOL command

Shared Pools - Reminder Of How They Work
Shared Pools Example:

Memory Concepts Can Be A Bit Complicated…
On top of all that, many of you might have performance
adjuster turned on…where memory is being adjusted on the
fly…Next, we have a virtual world where memory can now be
shared between LPARs!?!
With all that complexity, you can see why its so important to
be able to measure memory effectively
So lets see how easy it is

Machine Pool Memory / Memory Best Practice Guidelines
Audience Poll
Why do I ask the question?
MACHINE POOL IS THE MOST IMPORTANT POOL ON YOUR SYSTEM
Industry best practice guideline: < 10 Faults / sec
Why Is It The Most Important Pool?
This is the pool that is used for all the system tasks (operating system)

Machine Pool Memory / Best Practice Guidelines
If you have excessive faulting in the machine pool, your system will not be
running efficiently.
More importantly, if the system is not running efficiently…
Will your production applications (i.e. order entry) run efficiently?
Like a car not firing on all cylinders…I can get to the store, but my gas
mileage is horrible and I get there not as fast I normally would

CalculatingThe Machine Pool Memory Size
Best practice guideline:
the pool size should be 2 to 4 times the reserve size

Calculating The Machine Pool Memory Size (cont)
370 M
X2
----------
740 MB
Remember it’s a starting point – Your environment may require less/more memory
The key is to measure the pool faulting rate

Measuring Machine Pool Faulting
Old way – back in the day…the refresh
That simply tells us what’s happening now…

Measuring Machine Pool Faulting
To better manage memory, we need to answer these questions:
What’s been happening historically to the machine pool?
Is the machine pool faulting rate within the best practice guideline?
Service Level View & Historical View – lets see this now…

Tuning Machine Pool Faulting
Real Life Example:

Tuning Machine Pool Faulting (cont)
Wow…an 83%
Improvement!

Tuning Machine Pool Faulting (cont)
Wow…an 83%
Improvement!

Tuning Machine Pool Faulting (cont)

Techniques To Measure The Memory Component
Understanding Your Current Environment
What Is Your Faulting Factor?
Historical Total Faults Analysis
Identifying The Top Faulting Memory Pools
Performance Adjuster - Are You Set Up Efficiently?

Techniques To Measure The Memory Component
Understanding Your Current Environment

Techniques To Measure The Memory Component
Understanding Your Current Environment

Techniques To Measure The Memory Component
What Is Your Faulting Factor?
Mike Denney from IBM Wrote A Great Article Called: “Analyze This”
Introduced the concept: Faulting Factor
Based many factors…CPU time, Sync Disk Time, and Faulting Time
Although really cool, it’s a bit complicated
But MPG made it really easy for you!!

Techniques To Measure The Memory Component
MPG made Faulting Factor Easy!
Think of a 1 hour clock…
Job is In the CPU 30 minutes,
But that mean its also waiting 30 minutes
50% faulting factor
MPG Best Faulting Factor practice guideline: 30% or lower
What Is Your Faulting Factor? – Lets find out how easy it is!!

Techniques To Measure The Memory Component
Graph / Memory / Faulting Factor

Techniques To Measure The Memory Component
Historical Total Faults Analysis
Graph / Memory / Memory Size vs. Faulting

Techniques To Measure The Memory Component
Identifying The Top Faulting Memory Pools:
Current Day / Memory / Top Pools – do this for multiple days

Techniques To Measure The Memory Component
Identifying The Top Faulting Memory Pools

Techniques To Measure The Memory Component
Breaking down the top pools…

Techniques To Measure The Memory Component
Remember…
Understand Your Faulting Factor For All Periods During The Day
Understand Your Total Faulting Rate Historically
Understand Where Your Faulting Is Occurring – Month End
Measure Impact Of Any Changes

Techniques To Measure The Memory Component
Performance Adjuster – Am I set up efficiently?

Quick Refresher About Performance Adjuster
Performance Adjuster – Algorithm program that is moving memory in / out
of pools based on a set of conditions / configuration settings
Is it turned on?

Techniques To Measure The Memory Component
Is it turned on? – Easy To See in Performance Navigator

Techniques To Measure The Memory Component
Performance Adjuster – Am I set up efficiently?
Common Problem We See…Machine Pool Real Life Example
Memory going in / out of pool all day

Techniques To Measure The Memory Component
If machine pool is the most important pool…
Shouldn’t we keep memory in the pool so that the faulting rate remains
within the best practice guideline?
Absolutely!
How do we do that?

Techniques To Measure The Memory Component
Performance Adjuster – Am I set up efficiently?
Step 1 - Measure The Memory Activity In The Pool
Step 2 – Note The Avg / Min / Max for the pool memory activity
Step 3 – Do WRKSHRPOOL to analyze the tuning data configurations
(F11)
Step 4 – Compare PerfNav Avg / Min / Max to QPFRADJ
configuration settings
Step 5 – Make Necessary Changes
Lets see this now…

Techniques To Measure The Memory Component
Performance Adjuster – Am I set up efficiently?
Eventually we have something like this:

Techniques To Measure The Memory Component
Performance Adjuster – Am I set up efficiently?
Now we compare our PerfNav Findings to QPFRADJ settings:
What would happen with this kind of set up? – Poll Time!

Techniques To Measure The Memory Component
Performance Adjuster – Am I set up efficiently?
Here’s what would happen in the pool:

Techniques To Measure The Memory Component
Performance Adjuster – Am I set up efficiently?
New Memory Allocation Script

Advanced Techniques To Measure The Memory Component
Historical Analysis By Pool
Faulting Factor By Pool
Job Faulting
How Much Memory Does My Job Use?

Advanced Techniques To Measure The Memory Component
Historical Analysis By Pool

Advanced Techniques To Measure The Memory Component
Historical Analysis By Pool

Advanced Techniques To Measure The Memory Component
Faulting Factor By Pool

Advanced Techniques To Measure The Memory Component
Faulting Factor By Pool

Advanced Techniques To Measure The Memory Component
Job Faulting

Advanced Techniques To Measure The Memory Component
Job Faulting

Advanced Techniques To Measure The Memory Component
How Much Memory Does
My Job Use?
No memory usage metric
But you can be creative!

Advanced Techniques To Measure The Memory Component

Advanced Techniques To Measure The Memory Component

Why Do We Need To Measure The Memory Component?
Why Does Performance Navigator Make A Difference?
Perfect Real Life Memory Examples…