Distinguishing between optimization and tuning
You can use optimization and tuning separately or in combination to increase the performance of your application. Understanding the difference between them is the first step in understanding how the different levels, settings, and techniques can increase performance.
Optimization
Optimization is a compiler driven process that searches for opportunities to restructure your source code and give your application better overall performance at run time, without significantly impacting development time. The XL compiler optimization suite, which you control using compiler options and directives, performs best on well-written source code that has already been through a thorough debugging and testing process. These optimization transformations can bring the following benefits:
- Reduce the number of instructions that your application executes to perform critical operations.
- Restructure your object code to make optimal use of the PowerPC® architecture.
- Improve memory subsystem usage.
Each basic optimization technique can result in a performance benefit, although not all optimizations can benefit all applications. Consult the Steps in the optimization process for an overview of the common sequence of steps that you can use to increase the performance of your application.
Tuning
- Select more efficient machine instructions.
- Generate instruction sequences that are more relevant to your application.
- Select from more focussed optimizations to improve your code.
For instructions, see Tuning for your system architecture.
