Duration Performance Measurements - HP 64746 User Manual

Chapter 8: Making Software Performance Measurements

Duration Performance Measurements

Duration Performance Measurements
Duration measurements provide a best-case/worst-case characterization of code
execution time. These measurements record execution times that fall within a set of
specified time ranges. The analyzer trace command is set up to store only the entry
and exit states of the module to be measured (for example, a C function or Pascal
procedure). The SPMT provides two types of duration measurements: module
duration, and module usage.
Module duration measurements record how much time it takes to execute a
particular code segment (for example, a function in the source file).
Module usage shows how much of the execution time is spent outside of the
module (from exit to entry). This measurement gives an indication of how often
the module is being used.
When using the SPMT to perform duration measurements, there should be only two
addresses stored in the trace memory: the entry address, and the exit address.
Recursion can place several entry addresses before the first exit address, and/or
several exit addresses before the first entry address. Duration measurements are
made between the last entry address in a series of entry addresses, and the last exit
address in a series of exit addresses (see the figure below). All of the entry and exit
addresses which precede these last addresses are assumed to be unused prefetches,
and are ignored during time measurements.
When measuring a recursive function, module duration will be measured between
the last recursive call and the true end of the recursive execution. This will affect
the accuracy of the measurement.
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START - assumed prefetch
START - assumed prefetch
START - assumed prefetch
START - last ENTRY address -
END - assumed prefetch
END - assumed prefetch
END - assumed prefetch
END - last EXIT address
START - assumed prefetch
START - assumed prefetch
START - assumed prefetch
START - last ENTRY address -
END - assumed prefetch
END - assumed prefetch
Measure duration
-
Measure duration