Column: Embedded design


Finally, if we open a trace collected when


the application was compiled to use both the hard ABI and the NEON extensions, we see the view in Figure 9. Although there are still a few outliers,


we can see that the longest execution time now is a little less than 240 microseconds, reaffi rming the observation made that adding the NEON extensions considerably reduces the worst delay between calculation points.


Leverage In summary, we were able to leverage the LTTng library and Tracealyzer to quickly understand the impact of certain compiler options on the performance of userspace applications that perform fl oating-point calculations. Usually this sort of analysis is done when the application is completed, but the observed performance is deemed unacceptable and takes much longer. By using Tracealyzer during development to verify soſt ware timing, this situation was avoided.


Figure 7: Interval Timeline view


Figure 8: Interval Timeline view after adding the hard ABI option (but not the NEON extensions)


Figure 9: Interval Timeline view when the application was compiled to use both the hard ABI and the NEON extensions


www.electronicsworld.co.uk June 2021 11


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