Performance Profiling Overhead
Test RealTime - User Guide
maximum number of bytes, which is the sum of the sizes of all tracked blocks in the
queue.
Performance Profiling Overhead
For any source file containing at least one observed routine, a 24 byte structure is
declared at the beginning of the file.
The size of the global data storing the profiling results of an instrumented routine is
4+3*
t
bytes where
t
is the size of the type returned by the clock retrieving function.
See the Target Deployment Guide for more information.
Runtime Tracing Overhead
Implicit default constructors, implicit copy constructors and implicit destructors are
explicitly declared in any instrumented classes that permits it. Where C++ rules
forbid such explicit declarations, a 4 byte class is declared as an attribute at the end of
the class.
Reducing Instrumentation Overhead
Rational's Source Code Insertion (SCI) technology is designed to reduce both
performance and memory overhead to a minimum. Nevertheless, for certain cross-
platform targets, it may need to be reduced still further. There are three ways to do
this.
Limiting Code Coverage Types
When using the Code Coverage feature, procedure input and simple and implicit
block code coverage are enabled by default. You can reduce instrumentation
overhead by limiting the number of coverage types.
Note The Code Coverage report can only display coverage types among
those selected for instrumentation.
Instrumenting Calls (C Language)
When calls are instrumented, any instruction that calls a C user function or library
function constitutes a
branch
and thus generates overhead. You can disable call
instrumentation on a set of C functions using the Selective Code Coverage
Instrumentation Settings.
For example, you can usually exclude calls to standard C library functions such as
printf or fopen.
Optimizing the Information Mode
When using Code Coverage, you can specify the Information Mode which defines
how much coverage data is produced, and therefore stored in memory.
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