Types of Measurements
HP Caliper is capable of three types of performance measurement:
•A global measurement of total run metrics
•A sampled measurement based on the granularity you specify
•A precise measurement of every execution path in your code
Global Measurement
A global measurement gives you a single value for a specific metric of your program, such as total CPU time used.
The only global measurement available in HP Caliper is ecount (total CPU time).
A global measurement is best used for:
•Comparing the effect of different types of test data that your program processes
•Comparing the benefits of different
•Detecting performance regressions caused by program modifications
You can use a global measurement to help you identify what performance areas of your program to investigate further.
The advantage of a global measurement is that it does not affect your program's performance.
The disadvantage of a global measurements is that it does not identify specific parts of your program that might benefit from optimization.
Sampled Measurements
A sampled measurement measures your program's performance at regular intervals, based on CPU events, recording the current program location and selected performance metrics.
A sampled measurement is best used for:
•Identifying where your program is spending time
•Identifying approximately where events such as cache misses occur
•Determining the performance effect and location of branch mispredictions
You can use sampled measurements to focus your analysis on specific parts of your program.
The advantage of sampled measurements is that they can help you localize performance issues in your program.
The disadvantage is that they might miss very fast,
Sampled measurements also require more resources, such as system memory, which might affect the
You can control the tradeoff between resource usage and accuracy of the results by changing the sample interval.
Precise Measurements
A precise measurement gives you exact information about what is happening and where events are happening in your program. When you use a precise measurement, HP Caliper dynamically instruments your binary program while it is running to enable the collection of information.
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