In this blog post, we will take a look at the new resampling capabilites of Silk Performer 16. You can now resample both a single .tsd file as well as an entire load test. To do so, you can either redefine the timeframe or change the sample interval. We will explain both possibilities in depth based on an example. Take a look at the image below. In essence, it illustrates what resampling means and how it can affect the results. The two ways to resample results There are two ways to resample the results of a load test. You can ... (1) redefine the timeframe, or (2) redefine the interval Let's start with the first possibility: Often, users want to get rid of the data from the starting-up and cooling-down phase of a load test. This is the time, when the virtual users are gradually started or finished. Usually, you don't need the result data from these stages, so it can be a good idea to virtually cut them away and retain just the data from the steady state. With resampling, you can do just that. The second possibility is useful if you want to reduce the amount of the gathered result data or if you want to smooth out complex and spiky charts. In such a case, you can increase the sample interval of a load test. If the load test initially sampled data every 10 seconds, you can increase that value to - for example - 60 seconds. Depending on the duration of the load test, you can drastically reduce the amount of data. Adding load test results To see how this actually works in a real-world example, we have to open Performance Explorer and add some load test results to the workspace. So, let's click Load Test Results in the Add group on the Results tab. Select a project, choose a load test and click Finish . The result data displays in the tree on the left side and an overview report shows up. Let's take a look at the Active Users chart in our overview report. It seems that the interesting part of the load test begins at around 19:06 and ends at around 19:41. So, we're going to resample the data to this timeframe. Redefining the timeframe Now, on the Results tab, in the Data Processing group, we click Resample Load Test . Usually, the source and target directories are already set correctly. So, leave the default values and click Next . On the subsequent dialog, we enter the above mentioned values ( 19:06 and 19:41 ), leave all the other settings as they are, and click Finish . When the resampling is done, the resampled data displays in the tree and a new overview report opens. When we compare the charts of the two overview reports side by side, we can immediately see that the starting-up and cooling-down phase of the load test have been cut away and that the information from the steady state has been preserved. When you now take a look at the chart on the bottom right, you can see that the graph is quite a bit spiky. Let's try to smooth out this graph and make it a little more eye-friendly. Redefining the interval To do so, we will simply change the sample interval. Make sure you have the resampled data selected, then follow the same steps as described above: On the Results tab, in the Data Processing group, click Resample Load Test . Again, leave the default directory settings and click Next . Now, in the subsequent dialog, simply increase the Interval . That can be any multiple of the current value. In our example, we've increased the interval from 10 seconds to 60 seconds: Click Finish to start the resampling process. Again, the resampled data displays in the tree and a new overview report pops up. If you now compare the charts of the two overview reports, you'll see that the graph of the bottom right chart is considerably smoothed out: Conclusion Resampling load tests is quick and easy with Performance Explorer 16. Just define new date/time values or a new output interval and let Performance Explorer do the processing work. Remember that you can also resample single result files. For more information around resampling, you can take a look at the Silk Performer Online Help. The Online Help also contains comprehensive information about all the other features and functionality of Silk Performer and Performance Explorer. Here are some links: Resampling Load Tests Resampling Single Result Files Performance Explorer Watch the Resampling Load Tests Video You can also watch the following video to learn how to resample load tests in Performance Explorer 16. (Please visit the site to view this video) More information To learn more about all new features and enhancements Silk Performer 16.0 provides, take a look at the following blog posts: Network Emulation Offline Scripting Released: Silk Performer 16.0 In the Silk Performer documentation, you can also find detailed information about all new features: What's New in Silk Performer 16.0
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