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re: How To: Understand and calculate Virtual User "footprint"

Information about  the footprints for Vugen is good. this will help me for future performance testing environemnt.  I would also appreciate if you put some light on calculation of Pacing between two iteration.

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Information about  the footprints for Vugen is good. this will help me for future performance testing environemnt.  I would also appreciate if you put some light on calculation of Pacing between two iteration.

Hi Mark.

There was a question that I had related to the Memory footprint of the LR 9.1 sheet, which is pasted at this location.


The question is why is the CPU usage for the medium script higher than the simple script

                                                              Vusers          CPU%

WEB (Http/Html) High 50 3.1

WEB (Http/Html) Medium 50 12.5




Hi Krishnakanth,

I must admit that the creation of that old "vuser memory footprint" document was before my time here as the PM for LoadRunner.  If you comprehend the this blog entry (above), you will find that it is more important for you to learn how to calculate the memory footprint of your virtual users as you have built them for your test rather than to simply have a chart of static data for "empty vuser" comparisons.

What good is it to know the memory requirement for an "empty" virtual user that has no steps, actions, parameters or data?


Hi Mark

Thanks for the info. Another question. Is it possible to know the number of Vusers a particular protocol for a standard NT machine. A rough number, because, I am sure you understand, it would not be possible to do a research for a number of users for each and every protocol.

I used to do this a lot when I did Java (general template) doing a Java RMI app testing.

It helps in wedging in every Vuser you can into memory and determining your available CPU so that you can create a repeatable test that you do not have blame your load generation for creating problems.

I also found that if you are writing custom code, characterize mmdrv footprint overtime. It may help if your script varies in memory consumed. You may also find you wrote inefficient code that needs to be corrected. It can be very important if you are near the memory limit on your generators and you have a 1000 vuser group that varies in size by 1MB over time. It can be enough to crash your test.

Fortunately I never had that issue because I spent a lot of time characterizing my memory footprints before running them in a large scenario. Especially soak tests. It is definitelty worth the extra effort.


Hi Mark,

We have noticed that when running LR, that the memory usage does not flat line after all of our virtual users are ramped up into our sys for tests, as we had expected. Instead the injector resources specifically memory continue to get consumed as steadily as virtual users ramp up and after all users are logged in and performing their actions for the test. Can you explain?



I am looking to procure HP LoadRunner license to conduct performance/stress testing.  If I want to simulate up to 2000 concurrent users, what level of licensing do I need to procure.  How does virtual user license relate to simulated concurrent users?


I am new to LoadRunner and trying to understand more of its capabilities. Is there support for testing/evaluating over wireless networks like WiFi, WiMAX or 3G?

- Jigar

Hi Mark,

Great Info Thanks.

Would the number of VUSERS on a Load Generator cause Response Time variations. Also will the load on the VUSER have an Impact on the Response time ?

I am sorry if these questions are naive.


- G


Hi Mark,


1.)    We’re planning to simulate 1000 vusers for SAP system; do you guys have ideas on what specs or how many Loadrunner machines we need to cater all 1000 vusers for SAP?

2.)    I tried running a test using a single load generator for 150 vusers in SAP (LoadGen specs: 4GB RAM / 20GB Hard disk), what happen is when I hit 80 vusers suddenly all others vusers are getting failures (by this time, the memory utilization of the LoadGen is around 3GB), the common error I’m getting is ‘Abnormal termination, caused by mdrv process termination’. My question is do you think the error I’m getting is due to memory outage? If not, is there any other way I can prevent this from happening?


Your response will be very much appreciated



Mat Villanueva

Payal Dam



I need help on TruClient Web Protocol. I want to know how much memory a TruClient Vuser consumes. I dont see any information regarding TruClient Web Protocol in FootPrint Excel. Kindly help me with my request.

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