The LoadRunner Analysis tool can either be a godsend or the devil’s daughter. I think most Performance Analysts have a love-hate relationship with the Analysis tool…and refer to it as some sort of necessary evil.
With a little bit of patience, the Analysis tool is actually quite powerful and can be used to produce some fantastic graphs and information for your reports.
Everyone seems to learn their own tricks, and I’ll include some that we tend to use here at JDS. If you have any more of your own, please submit these as comments.
In no particular order:-
- Setting the Granularity.
The granularity affects the graph smoothing, or number of data points. A high granularity value will reduce clutter and improve readability, but it may hide events such as spikes. The trick is to adjust the granuarity to maximise readability but accurately represent any important events. Caution, however for larger performance tests setting the granularity too low may cause the Analysis tool to hang for a few minutes.
- Annotations – Comments and Arrows.
Make use of comments and arrows to annotate important events on the graph. In addition, these are useful for labelling data lines…particularly when there are lots of lines and you want to highlight just one of two of them.
- Focus on just a few transactions.
Performance tests can have sometimes hundreds of transactions and this can generate some very busy graphs. Decide on 3-5 transactions that have the highest business value or are of particular interest…focusing your analysis on just a few transactions is more valuable to the readers of your report.
- Set your Y-Axis to be the same for all graphs.
Graphs should be easily comparable and “tell the same story”. By default the Y-Axis is set to Automatic, which sets the minimum and maximum scale to match your data. Go to Display Options > Advanced > Axis tab, and change Minimum and Maximum values from “Auto” to something sensible. Percentage graphs should always be ranges from 0% to 100%.
As a general rule, your Y-Axis scale should always start at zero and your ideal or SLA level should be approximately one-third up the scale. People we automatically assume response times in the lower third of your graph are “good” and the upper two-thirds are “poor”.
- Tell a Story
All graphs you present via the Analysis tool should tell a story. Performance Testing is there to answer the question of whether the application will scale to the load level required in production…and as a performance analysis you should produce graphs to provide evidence of either the success or failure of this performance testing.
- Don’t Take Screenshots with the Print Screen button
Screenshots look bad, instead use Edit > Copy To Clipboard > Graph. Alternatively, you can export graphs as image files. Go to Display Options > Advanced > Export tab. By exporting in Metafile format you will avoid any blocky pixelation which looks great for presentations or printed reports. I also recommend setting the border background colour to White for a nicer look (Display Options > Advanced > Chart > Panel > Background > Color).
- Filter on Peak Load
When analysing a peak load test, make use of a global filter to limit your analysis to the time that was spent AT PEAK LOAD, so that your response times do not include values measured during ramp up.
- Percentile Graph Analysis
Look at each response time in the percentile graph to see if there are any weird “step” patterns. The lines in the percentile graph should always be smooth, if there is a weird “step” pattern that could indicate abnormal behaviour.
- Import External Data
Remember that you can import data from external monitors/text files (Tools > External Monitors > Import Data).
- Merging graphs
This is useful but don’t put too many values on the graph, or it will be hard to interpret. Combine multiple data types can be confusing. Use Annotations.
- Edit the Transaction Summary in Excel or Word.
The Transaction Summary can be easily copied and pasted into either Word or Excel, this allows it to be easily edited. For example, removing columns and reduced the decimal points displayed.
- Only use Complete Data
After initially opening a LoadRunner result, only summary data is available. In the lower-left corner, you will notice the generation of Complete Data. You should always wait until this background process completes before editing graphs.
- Remove the data point markers
Use Display Options > Graph Type to quickly remove all the data point marks for your line graph. This makes it look a lot less cluttered.
- Make use of Templates
This feature (Tools > Templates) allows you to quickly apply the same graphs and formatting from one Analysis scenario to another. This is great for comparing results, however always double-check filters to after applying a template to ensure you are not filtering out any important data.
I hope you all find this bag of tricks useful. I know I’ve learnt a thing or two by putting it together. ;-)