Step load pattern relation

Question

What is relationship between step load pattern and load step duration? I'm trying to load 100 vusers in increasing manner with duration of 20 mins. But it does not reach max user load of 100. Can somebody explain the calculation of how much value to specify in load step pattern and load duration so that max vuser can be achieved?

Answer 1

Let's run through a Step Load pattern

The start user count is how many users to simulate at the start of your test. 
Step duration is how long to run at the user count until we increase the user load.
Step user count is how many users to add each step duration.
Maximum user count is the maximum users we will simulate before we stop increasiung the simulated user count. 

As an example:
Start User Count: 10
Step Duration:60 (seconds)
Step User Count:5
Maximum User Count: 100

When your load test starts it will simulate 10 users.  Every 60 seconds it will add 5 users until the maximum of 100 users is reached.

From 0-1 Minuites we will simulate 10 users
from 1 -2 Minutes we will simulate 15 users
from 2 -3 Minutes we will simulate 20 users
from 3 -4 Minutes we will simulate 25 users
...
from 18 minutes until the test is over we will simulate simulate 100 users

 

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Tim

Answer 2

Thanks anyways, I'm aware of this explaination. My question is how does it relate to no. of iterations or load step duration, i mean what option should be selected inorder reach max users? Also what should be test mix compose of ? I know it defn makes a difference.

Answer 3

Hello,

If the total test duration is shorter than the time that is required to step up to the maximum user load, then the test stops after the elapsed duration and does not reach the Max User Count target. There is no option to change this rule.

For more detailed information, you can refer to this article:
http://msdn.microsoft.com/en-us/library/ms182564.aspx

The test mix specifies the probability of a virtual user running a given test in a load test scenario. This lets you simulate load more realistically. After you add a set of tests to a load test, the test mix works like other mix options. A virtual user randomly selects a test, based on the probability you specified in the mix.

For more detailed information, you can refer to this article:
http://msdn.microsoft.com/en-us/library/ms182565.aspx

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Answer 4

Hi all,

can we make step load test on unit test ?

Or is only for web test ?

Thank you

Winzo

Answer 5

Hello Winzo,

Yes, we can make it for unit tests.

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Send us any feedback you have about the help from MSFT at [e-mail].

Answer 6

Hi,

actually I made some step load test with my unit test but the step duration is not equal at the number written in the wizard !
All documentations are about web test that is why I believed that.

Can you explain me which properties must I choose in the wizard to create a step load test which respects the step duration, please ?
ex :
min user :10
max user :100
step duration :10s
user per step :10

According to me, I will have 100 users in about 90s and only 100 test.
But I have more than 100 tests because the users are loaded faster and reused.

Thank,

-Winzo

Answer 7

Winzo -

You are assuming that each user executes a single test each step duration but that is not the case.  Each user will execute as many tests as possible (given the actual test time, think time, and resource limitations).  Look at the table below, even if each test takes 10 seconds and we stop the test 10 seconds after you have reached your max user count we expect to see a lot more than 100 tests throughout the load test given your configuration. 


Time  Users  tests  Total Tests
10     10       10      10
20     20       20      30
30     30       30      60
40     40       40      100
50     50       50      150
...
100   100     100    550

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Tim

Answer 8

Hi TimJim,

I understand the step load profile, better now ! Thank.

One more question please :

I configure my step load like this :
min user :0
max user :10
step duration :10
user per step :1

I also  put a " System.Diagnostics.Debug.WriteLine" to trace the userid and the isnewuser properties.

If I understand your last post, I should have
userid to 0 and isnewuser at true, then
userid to 0 and isnewuser at false
userid to 0 and isnewuser at false
userid to 0 and isnewuser at false
userid to 0 and isnewuser at false
..., then
userid to 1 and isnewuser at true
userid to 0 and isnewuser at false
userid to 1 and isnewuser at false
userid to 0 and isnewuser at false
userid to 1 and isnewuser at false
...


but I get :
userid to 0 and isnewuser at true
userid to 1 and isnewuser at true
userid to 2 and isnewuser at true
userid to 3 and isnewuser at true
userid to 4 and isnewuser at true
userid to 5 and isnewuser at true
userid to 6 and isnewuser at true
userid to 7 and isnewuser at true
userid to 8 and isnewuser at true
userid to 9 and isnewuser at true
userid to 0 and isnewuser at false
userid to 1 and isnewuser at false
userid to 2 and isnewuser at false
userid to 3 and isnewuser at false
...

And the step duration is not respected !

Do you know this problem ?

Thank
-Winzo

Answer 9

Winzo,

If this doesn't answer your question you may want to start a new thread and see if a Microsoft moderator chimes in as these are implementation details most of us wouldn't be familiar with.

I believe the IsNewUSer property is driven by your “Percentage of New Users” property.  Select your load test scenario and play around with the "Percentage of new users" setting and see how that effects your numbers.

See the section titled "Choose a value for the “Percentage of New Users” property" in the following link for a description
http://blogs.msdn.com/billbar/articles/517081.aspx

UserId is discussed a little bit in this link:
http://blogs.msdn.com/edglas/archive/2006/02/06/525644.aspx

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Tim