if you have a transaction processing system,

8/14/2019 If You Have a Transaction Processing System,

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If you have a transactionprocessing system,

John Meisenbacher

[email protected]


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I can create a simpleaccurate CPU performance

modelthat can help you make

your system more efficient


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in one week

with the data you alreadycollect.


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And so can you !


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Performance model

A performance model provides thequantitative information you need to:

Manage the performance of your system

and Understand the impact of:

Software changes

Hardware / configuration changes and Actual / projected transaction load

changes.


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CPU performance model

The best model is only as complex as itneeds to be to provide information thatis sufficiently accurate to help you

make the right decision. This model focuses on the CPU

Not memory

Not file I/O

Not network bandwidth Not transaction latency

CPU is typically the constraining


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Performance

Support capacity planning to properly size the hardware system

required by the software intensive

transaction processing system. Identify performance changes

With changing hardware, software, andtransactions.

Isolate performance issues within thesystem.


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But first a word about

You should understand the basicfeatures of most transactions in thereal world.

The rate, transactions per second(TPS), varies: During the day there are peak hours

During the week there are peak days During the year there are peak months /

seasons


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Daily transaction cycles


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The question

Is my hardware (CPU) properlysized to support my peak

transaction period in mynext peak season?

Possible ways to answer thequestion: Use a commercial capacity planning tool.


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Commercial capacityl nnin t l

Commercial capacity planning toolstypically focus on system size, acutesystem issues, and hardware

projections. These tools typically do not easily

integrate with transaction rates andtherefore cannot model transactionsystems.

They may be good for monitoringand alerts but unless transaction


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Daily CPU usage pattern


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Build a performance testnvir nm nt f r th

1. Build and maintain a hardware testenvironment as close as possible toproduction.

2. Load production software and build adatabase as close as possible toproduction.

3. Develop a way to send production like

transactions through the system.4. Floor it. Max out the system to seewhen it breaks.

5. Hope your test setup is close enough


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Build a CPU model of the

A CPU model of the transactionprocessing systems integrates threeperspectives:

1. Business the transactions processed.

2. Capacity Planning the hardwaresystems used to process the

transactions.3. Software Engineering the software

intensive systems and databases that


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Rise and fall of

Most online real world transactionsrise and fall during the day, week,month, and year.

The method takes advantage ofthese cycles.

Multiple data points are used for

correlation analysis. The approach can be used in


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Transaction processing andP


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Data reported in time

Report data around the peak period. CPU usage in some time increment, generally

between 10 and 20 minutes. (15 minutes iscommon)

Shorter time periods provides more data andvariation but may not improve accuracy. Longer time periods require less data and hides

variation reducing accuracy and precision.

Transactions are typically logged by time.

Report the number of transactions in the sameincrement used for CPU usage. If the processing demands of different transactions

vary significantly then report the rates separately.


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Create the model

Excel is sufficient to correlate theinformation Graphically displayed for human analysis Quantified for modeling and projections

Simply defined from the previous graph: CPU utilization = CPU per TPS * TPS +

overhead y = a*x + b

System capacity is the TPS rate that drivesthe system to your safe limit, such as 80%CPU utilization.TPS Limit = (Safe CPU limit overhead ) /


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Graph of correlation shapes


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Correlate TPS and CPU


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Transaction processing

The software intensive systemtypically includes processes relatedto transactions:

The actual transaction processing Data management for look-ups and

logging Communication processing Format conversion

As well other processes, such ass stem monitorin , that are


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CPU divided by type of


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Use the model to manage thet m

Using the previous graph What can wechange to avoid purchasing additionalhardware for the upcoming peak season? Improving communication and format conversion

provides limited benefit. The transaction or database process might be

made more efficient. Wide swings in other processes, independent of

transactions, should also be addressed.

The change, in this real-world case, was madeto transaction replication in the database.

The release was rolled out into product and anew model created.


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System After ApplicationP rf rm n M ifi ti n


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Manage performance within ar l

The precision of the model can be used tomeasure changes in the system.

Data from the previous day can be collectedand quickly analyzed to determine ifchanges to the system have improved ordegraded performance.

In the next graph several changes, such asincreased monitoring that was backed out

and improvements in other scripts areplotted as over a one month period leadingup to peak season.


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Variation of system capacity

Monitoring Scripts

And

Other scripts optimized

OK after OK during peak


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Work with system experts

In the previous examples the business wassupported through cooperation betweencapacity planning and software experts.

Creating the model, generally fairly easy, is

only the first step. You must use work with developers or

vendors to successfully manage and adjustsystem performance.

The model provides quantitative informationto evaluate the system and determine ifadditional hardware is necessary or if thereis a more cost effective solution but thisre uires our ex erience and insi ht.


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Trust your experience and

I would like to say that the modelprovides all the answers on a silverplatter.

However (as you know), there is nosilver platter for capacity planners andsystem owners.

Use the model along with yourunderstanding of hardware and

software systems to direct your analysisand decision.

And then collect more production data


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Good luck !

I hope you have found this presentationinformative.

Please try this technique if you thinkit might help and, if you could,

please let me know what worked

and didnt work for you.

if you have a transaction processing system,

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