Guidelines

Recommendations for correctly using and interpreting the results of SPE profiling:

• The bars showing the number of SPE samples for source code lines are for visually comparing the relative number of SPE samples between different lines of code within this profile. A full bar indicates that more events were sampled on a specific source code line than on the others.
• Arm® MAP handles SPE data in a time-agnostic manner: the numbers reported in the SPE Tables tab are from the entire program run, and from across all threads. Selecting a time range or using a Main Thread Only view mode does not change what is reported by the SPE Tables tab or the SPE source code annotations.
• To keep the impact of enabling SPE profiling to reasonable levels, Arm® MAP only utilizes a subset of the samples taken by SPE. Therefore, the number of SPE samples (hits) that are taken, depend on a number of factors that can vary between profiled applications, host machine configuration, and versions of Arm® MAP.
• You can use SPE profiling in conjunction with the Configurable Perf metrics feature. Arm recommends that you enable the CPU instruction metrics which relate to the SPE filter you are using. For example, using the branch-misses CPU instruction metric with the mispredict SPE filter. The CPU instruction metrics are both time-based and accurate counts, mitigating some of the limitations mentioned here.