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Performance tuning is the improvement of system performance. This is typically a computer systems. The motivation for such activity is called a performance problem, which can be real or anticipated. Most systems will respond to increased load with some degree of decreasing performance. A system's ability to accept higher load is called scalability, and modifying a system to handle a higher load is synonymous to performance tuning. Systematic tuning follows these steps: # Assess the problem and establish numeric values that categorize acceptable behavior. # Measure the performance of the system before modification. # Identify the part of the system that is critical for improving the performance. This is called the bottleneck. # Modify that part of the system to remove the bottleneck. # Measure the performance of the system after modification. # If the modification makes the performance better, adopt it. If the modification makes the performance worse, put it back the way it was. This is an instance of the measure-evaluate-improve-learn cycle from quality assurance. A performance problem may be identified by slow or unresponsive systems. This usually occurs because high system loading, causing some part of the system to reach a limit in its ability to respond. This limit within the system is referred to as a bottleneck. A handful of techniques are used to improve performance. Among them are code optimization, load balancing, caching strategy, distributed computing and self-tuning. == Performance analysis == : ''See the main article at Performance analysis'' Performance analysis, commonly known as profiling, is the investigation of a program's behavior using information gathered as the program executes. Its goal is to determine which sections of a program to optimize. A profiler is a performance analysis tool that measures the behavior of a program as it executes, particularly the frequency and duration of function calls. Performance analysis tools existed at least from the early 1970s. Profilers may be classified according to their output types, or their methods for data gathering. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Performance tuning」の詳細全文を読む スポンサード リンク
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