Profiling
QT
RACE
-
U
SER
M
ANUAL
© 2018 PDQLogic Ltd.
QTrace User Manual Rev 1.01
Page 33
5.1
CPU timing
The
CPU Time Display
radio buttons allow CPU function timing to be displayed in different forms; as a
percentage of the overall number of executed CPU instructions or the number of CPU cycles (or seconds)
spent executing instructions in the function. The CPU clock speed needs to be known in order to display
execution time in seconds. This can either be the detected CPU clock speed or a manually entered value.
Note:
Because Cortex-M does not implement cycle accurate tracing, it is not possible to generate 100%
accurate timing results and so the displayed CPU timing figures should be used as a comparative
measurement.
The following points will affect timing measurement accuracy:
1.
Pipeline delays are estimated
2.
Argument dependant instruction times use an average of min/max execution times
3.
Function timing does not include nested calls
4.
Timing calculations assume no memory wait states