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Note
Some compilers emit more than one symbol for certain addresses.
For example, a compiler may emit "math_library" and
"_math_library" for the first address in a routine named
math_library. The analyzer will show the first symbol it finds to
represent a range of addresses, or a single address point, and it will
show the other symbols under either "Symbols within range" or
"Additional symbols for address", as applicable. In the
"math_library" example, it may show either "math_library" or
"_math_library" to represent the range, depending on which symbol
it finds first. The other symbol will be shown below "Symbols
within range" in the report. These conditions appear particularly
in default measurements that include all global and local symbols.
Relative and Absolute Counts. Relative count is the total
number of states associated with the address ranges in the
performance measurement. Relative time is the total amount of
time associated with the address ranges in the performance
measurement. The absolute counts are the number of states or
amount of time associated with all the states in all the traces.
Error Tolerance and Confidence Level. An approximate error
may exist in displayed information. Error tolerance for a level of
confidence is calculated using the mean of the standard deviations
and the mean of the means. Error tolerance gives an indication of
the stability of the information. For example, if the error is 5% for
a confidence level of 95%, then you can be 95% confident that the
information has an error of 5% or less.
The Student's "T" distribution is used in these calculations because
it improves the accuracy for small samples. As the size of the
sample increases, the Student's "T" distribution approaches the
normal distribution.
4-14 Performance Measurements
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