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How is the response time contributions calculated in complex service flows?

kevin_aird
Newcomer

I have been trying to explain to a project how response time
contribution is calculated in a Service Flow diagram. I have been referring to
this answer but came across an inconsistency in the calculation results for
more complex service flows. Can someone please tell me how response time
contributions are calculated and why my calculations seem to be off in Example
#2 attached?

Excel calculations examples-calcs.xlsx

In Example 1 –



  • In
    this case I am using the service flow for a single PurePath

  • The
    calculations in this case are mostly adding up – The response time
    contribution calculation matches the contribution reported in the service
    flow


In Example 2 –



  • For
    this case I use a service flow analyzing approx. 2k transactions.

  • Using
    the same formulas from example 1, the response time contributions no longer
    match what we're seeing in the Service Flow

  • There's
    some asynchronous invocations in play here. But even the contribution
    calculation for the Web Tier, which is upstream to the async calls, does
    not match what is reported in the service flow


The formulas I'm
using:

  • (Average
    time per Tier) = (Average
    Response Time) x (Call Percentage) x (Calls per request)
  • (Calls per request) = (Requests) / (Consuming API.Requests)
  • (Response Time Contribution) = (Average time per Tier) /
    (Consuming API.Average Response Time)

Note: The first formula I got from this answer: https://answers.dynatrace.com/questions/200720/how-is-the-response-time-contribution-in-service-f.ht...


2 REPLIES 2

sebastian_kryst
DynaMight Leader
DynaMight Leader

I understand this like this

We have something like this:

Root —- A(60%) —- B (70%). —- C (20%)

This means that on A we spent 60%, from this time 70% was spent on component B (from root it will be x*0.6*0.7)

From this time 20% was spent on component C so x*0.6*0.7*0.2

Sebastian


Thanks for the reply Sebastian. So please correct me if I'm misinterpreting your answer. But from that I'm getting this formula:

(Average Time on C) = (Average Time on Root) x (Response time Contrib on A) x (Response time Contrib on B) x (Response time Contrib on C)

which becomes this formula (when trying to get the contribution time on C):

(Response time Contrib on C) = (Average Time on C)/( (Average Time on Root) x (Response time Contrib on B) x (Response time Contrib on A) )

When I try to apply this new formula to the two examples in my note however, the results still do not match the response time contributions reported on the Dynatrace Servce Flow. Are there any other factors I'm missing here?