Load Test: Different values for counters in graph and table view?

Sometime while looking at load test results you may see different values for some counters in Graph view and Table view.   Generally Min and Max values are different. e.g for my load test result I am seeing different values of counter Page response time in table and graph as you can see below

 

 

It’s bit confusing as 2 different values are there so which one to rely upon for analysis. In this post, I’ll explain why the values are different and which one you can use for deeper analysis.

Actually graph shows you samples at various instances of time which depends upon sampling interval. For each interval, an average is computed for all the requests that were processed during that interval. So, say in the first interval, there are 2 requests processed – one with 2 sec and other with 4 sec, the average for the interval is 3 sec. This is what we show in graph. If the request with 2 sec happens to be the absolute min, the samples graph has not captured it, but the table view will show it. If that interval’s average, 3 sec, is min across all sample intervals, we show 3 sec as min in samples graph. Same explanation goes with max.

In short, graph view shows averages of intervals and hence cannot show absolute min/max. So in case you need absolute min / max data for a counter then table view is more appropriate place to get that data.

Let me know in case of any Qs / issues around it. You can post your query here as well.

Comments

• Anonymous
  April 05, 2012
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