Performance tuning
Encyclopedia
Performance tuning is the improvement of system
performance
. This is typically a computer application, but the same methods can be applied to economic markets, bureaucracies or other complex 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:
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, 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.
Performance engineering is the discipline encompassing roles, skills, activities, practices, tools, and deliverables used to meet the non-functional requirements
of a designed system, such as increase business revenue, reduction of system failure, delayed projects, and avoidance of unnecessary usage of resources or work.
Several common activities have been identified in different methodologies:
Ezation include improving the code so that work is done once before a loop rather than inside a loop or replacing a call to a simple selection sort
with a call to the more complicated algorithm for a quicksort.
The methods used to determine which data is stored in progressively faster storage are collectively called caching strategies.
and can improve over-all performance.
Load balancing is often used to achieve further gains from a distributed system by intelligently selecting which machine to run an operation on based on how busy all potential candidates are, and how well suited each machine is to the type of operation that needs to be performed.
is used to increase ng the potential for parallel execution on modern CPU architectures continues, the use of distributed systems is essential to achieve performance benefits from the available parallelism
. High performance cluster computing is a well known use of distributed systems for performance improvements.
Distributed computing and clustering can negatively impact latency while simultaneously increasing load on shared resources, such as database systems. To minimize latency and avoid bottlenecks, distributed computing can benefit significantly from distributed cache
s.
or error minimization. Self-tuning systems typically exhibit non-linear adaptive control
. Self-tuning systems have been a hallmark of the aerospace industry for decades, as this sort of feedback is necessary to generate optimal multi-variable control for nonlinear processes.
In the process of finding and removing bottlenecks, it is important to prove their existence, such as by sampling, before acting to remove them. There is a strong temptation to guess. Guesses are often wrong, and investing only in guesses can itself be a bottleneck.
System
System is a set of interacting or interdependent components forming an integrated whole....
performance
Computer performance
Computer performance is characterized by the amount of useful work accomplished by a computer system compared to the time and resources used.Depending on the context, good computer performance may involve one or more of the following:...
. This is typically a computer application, but the same methods can be applied to economic markets, bureaucracies or other complex systems. The motivation for such activity is called a performance problem, which can be real or anticipated. Most systems will respond to increased load
Load (computing)
In UNIX computing, the system load is a measure of the amount of work that a computer system performs. The load average represents the average system load over a period of time...
with some degree of decreasing performance. A system's ability to accept higher load is called scalability
Scalability
In electronics scalability is the ability of a system, network, or process, to handle growing amount of work in a graceful manner or its ability to be enlarged to accommodate that growth...
, 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 bottleneckBottleneckA bottleneck is a phenomenon where the performance or capacity of an entire system is limited by a single or limited number of components or resources. The term bottleneck is taken from the 'assets are water' metaphor. As water is poured out of a bottle, the rate of outflow is limited by the width...
. - Modify that part of the system to remove the bottleneck.
- Measure the performance of the system after modification.
This is an instance of the measure-evaluate-improve-learn cycle from quality assurance
Quality Assurance
Quality assurance, or QA for short, is the systematic monitoring and evaluation of the various aspects of a project, service or facility to maximize the probability that minimum standards of quality are being attained by the production process...
.
A performance problem may be identified by slow or unresponsive systems. This usually occurs because high system loading
Load (computing)
In UNIX computing, the system load is a measure of the amount of work that a computer system performs. The load average represents the average system load over a period of time...
, 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
Bottleneck
A bottleneck is a phenomenon where the performance or capacity of an entire system is limited by a single or limited number of components or resources. The term bottleneck is taken from the 'assets are water' metaphor. As water is poured out of a bottle, the rate of outflow is limited by the width...
.
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 analysisPerformance analysisIn software engineering, profiling is a form of dynamic program analysis that measures, for example, the usage of memory, the usage of particular instructions, or frequency and duration of function calls...
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.
Performance engineering
- See the main article at Performance engineeringPerformance EngineeringPerformance engineering within systems engineering, encompasses the set of roles, skills, activities, practices, tools, and deliverables applied at every phase of the Systems Development Life Cycle which ensures that a solution will be designed, implemented, and operationally supported to meet the...
Performance engineering is the discipline encompassing roles, skills, activities, practices, tools, and deliverables used to meet the non-functional requirements
Non-functional requirements
In systems engineering and requirements engineering, a non-functional requirement is a requirement that specifies criteria that can be used to judge the operation of a system, rather than specific behaviors. This should be contrasted with functional requirements that define specific behavior or...
of a designed system, such as increase business revenue, reduction of system failure, delayed projects, and avoidance of unnecessary usage of resources or work.
Several common activities have been identified in different methodologies:
- Identification of critical business processes.
- Elaboration of the processes in use cases and system volumetrics.
- System construction, including performance tuning.
- Deployment of the constructed system.
- Service management, including activities performed after the system has been deployed.
Code optimization
- See the main article at Optimization (computer science)Optimization (computer science)In computer science, program optimization or software optimization is the process of modifying a software system to make some aspect of it work more efficiently or use fewer resources...
.
Ezation include improving the code so that work is done once before a loop rather than inside a loop or replacing a call to a simple selection sort
Selection sort
Selection sort is a sorting algorithm, specifically an in-place comparison sort. It has O time complexity, making it inefficient on large lists, and generally performs worse than the similar insertion sort...
with a call to the more complicated algorithm for a quicksort.
Caching strategy
Caching is a fundamental method of removing performance bottlenecks that are the result of slow access to data. Caching improves performance by retaining frequently used information in high speed memory, which reduces access time and thus improves performance. Caching is an effective manner of improving performance in situations where the principle of locality of referenceLocality of reference
In computer science, locality of reference, also known as the principle of locality, is the phenomenon of the same value or related storage locations being frequently accessed. There are two basic types of reference locality. Temporal locality refers to the reuse of specific data and/or resources...
The methods used to determine which data is stored in progressively faster storage are collectively called caching strategies.
Load balancing
A system can consist of independent components, each able to service requests. If all the requests are serviced by one of these systems (or a small number) while others remain idle then time is wasted waiting for used system to be available. Arranging so all systems are used equally is referred to as load balancingLoad balancing (computing)
Load balancing is a computer networking methodology to distribute workload across multiple computers or a computer cluster, network links, central processing units, disk drives, or other resources, to achieve optimal resource utilization, maximize throughput, minimize response time, and avoid...
and can improve over-all performance.
Load balancing is often used to achieve further gains from a distributed system by intelligently selecting which machine to run an operation on based on how busy all potential candidates are, and how well suited each machine is to the type of operation that needs to be performed.
Distributed computing
Distributed computingDistributed computing
Distributed computing is a field of computer science that studies distributed systems. A distributed system consists of multiple autonomous computers that communicate through a computer network. The computers interact with each other in order to achieve a common goal...
is used to increase ng the potential for parallel execution on modern CPU architectures continues, the use of distributed systems is essential to achieve performance benefits from the available parallelism
Parallel computing
Parallel computing is a form of computation in which many calculations are carried out simultaneously, operating on the principle that large problems can often be divided into smaller ones, which are then solved concurrently . There are several different forms of parallel computing: bit-level,...
. High performance cluster computing is a well known use of distributed systems for performance improvements.
Distributed computing and clustering can negatively impact latency while simultaneously increasing load on shared resources, such as database systems. To minimize latency and avoid bottlenecks, distributed computing can benefit significantly from distributed cache
Cache
In computer engineering, a cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere...
s.
Self-tuning
A self-tuning system is capable of optimizing its own internal running parameters in order to maximize or minimize the fulfillment of an objective function; typically the maximization of efficiencyEfficiency
Efficiency in general describes the extent to which time or effort is well used for the intended task or purpose. It is often used with the specific purpose of relaying the capability of a specific application of effort to produce a specific outcome effectively with a minimum amount or quantity of...
or error minimization. Self-tuning systems typically exhibit non-linear adaptive control
Adaptive control
Adaptive control is the control method used by a controller which must adapt to a controlled system with parameters which vary, or are initially uncertain. For example, as an aircraft flies, its mass will slowly decrease as a result of fuel consumption; a control law is needed that adapts itself...
. Self-tuning systems have been a hallmark of the aerospace industry for decades, as this sort of feedback is necessary to generate optimal multi-variable control for nonlinear processes.
Bottlenecks
The bottleneck is the part of a system which is at capacity. Other parts of the system will be idle waiting for it to perform its task.In the process of finding and removing bottlenecks, it is important to prove their existence, such as by sampling, before acting to remove them. There is a strong temptation to guess. Guesses are often wrong, and investing only in guesses can itself be a bottleneck.
External links
- Tweaking Your System Performance In Windows XP - Easy to read guide on tuning computer performance.
- Online CPU and GPU - Optimization for video game technology
- performancetroubleshooting.com - Tips on Optimizing your performance