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  1. #1
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    Fluctuating response time (no errors) ramped up?

    Just curious. I have a processor-heavy application that I ramped up to 500 users over 15 minutes. There were hardly any errors. All users' transactions were able to complete their requests. However, looking at the response time results, i see two major regular peaks and troughs.

    So for minute 1-3 the response time will peak to 2 minutes, minute 3-6 will trough back down to < 25 seconds, then repeat again.

    What is the possible explanation for this?

    It doesn't seem as if the network is the problem. There are a lot of calls to a (slower) 3rd party process..

  2. #2
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    Re: Fluctuating response time (no errors) ramped up?

    1) Unless you have permission to test the third party processes as a part of your test then consider eliminating those calls if they are business process critical.

    2) if you are using virtual machines for your virtual user staging then you will have a higher degree of variability in your results set than with a physical machine. This is due to both how the hypervisor operates and cross virtual machine influences on your test.

    3) Consider a lightly loaded physical generator as a control point during your test to check to see if this is a resource bound condition on your load generator(s) or as a true application issue.

    4) Investigate the resoure set of Network, CPU, Disk and Network. Find out which resource is being impinged at the time point associated with the long response times. Your performance test tool should be able to assist you with the monitoring of your infrastructure during the test to help to address this question.

    Keep in mind that your question is a very very broad one, one where the answers could potentially fill several books.
    James Pulley

    Replace ineffective offshore contracts, LoadRunnerByTheHour. Starting @ $19.95/hr USD.

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  3. #3
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    Re: Fluctuating response time (no errors) ramped up?

    do you also have peaks and troughs in the throughput/hits per second graphs?

    if so it could be 'bunching'

    in that more of your users are executing code together around 1-3 minutes and then less are executing around 3-6 minutes

  4. #4
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    Re: Fluctuating response time (no errors) ramped up?

    First thing I'd do is slow down the ramp up & see if it persists, ie is it application or load dependent. Proceed from there... HTH

 

 

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