No data to show. Why your application does not consume enough CPU time?

With the Hotspot and Concurrency analyses a user might receive this message:

"No data to show. Your application does not consume enough CPU time to be measured by the statistical method employed in this product. Try to increase the time your workload runs or use Locks and Waits mode to gather performance data on your application."

Likewise, the Locks and Waits analysis may result with the similar message:

"No data to show. No Locks and Waits data was collected for your application because it did not wait on any synchronization or I/O objects. Use Hotspot and Concurrency analyses to gather other performance data on your application."

 

Looks really confusing, doesn't it?. Here are a few tips on why you might receive such messages. 


1. The application is really fast, indeed. If all that the application is doing is executing the main function that contains a few lightweight calculations without any system calls, it might take a few milliseconds to complete the program. Intel® Parallel Amplifier data collector collects samples nominally once each millisecond and the short application run doesn't provide enough samples to be statistically significant.

 

2. The application should do something significant in terms of consuming CPU, but usually runs in a few seconds. In this case, check the output of the application. There might be a situation when wrong parameters were passed and the program ended up with a diagnostic message (for example: because of wrong initial working directory or wrong command-line options, etc). Ensure that the application runs correctly.

 

3. The application was definitely running a considerable amount of time and should generate many data samples. This might be the most confusing case, since the Summary window reports that the application was running long enough to collect some data:

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In this case, there may be a configuration option that limits the data collection. Check the Parallel Amplifier Project Properties:

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If you see that the switch "Start data collection paused" is on, uncheck it and try running the analysis again.

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This option prevents the tool from collecting data until the Continue button on the toolbar is pressed.

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Einzelheiten zur Compiler-Optimierung finden Sie in unserem Optimierungshinweis.