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Software Profiling
In software engineering, profiling (program profiling, software profiling) is a form of dynamic program analysis that measures, for example, the space (memory) or time complexity of a program, the usage of particular instructions, or the frequency and duration of function calls. Most commonly, profiling information serves to aid program optimization, and more specifically, performance engineering. Profiling is achieved by instrumenting either the program source code or its binary executable form using a tool called a ''profiler'' (or ''code profiler''). Profilers may use a number of different techniques, such as event-based, statistical, instrumented, and simulation methods. Gathering program events Profilers use a wide variety of techniques to collect data, including hardware interrupts, code instrumentation, instruction set simulation, operating system hooks, and performance counters. Use of profilers The output of a profiler may be: * A statistical ''summary'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Engineering
Software engineering is a branch of both computer science and engineering focused on designing, developing, testing, and maintaining Application software, software applications. It involves applying engineering design process, engineering principles and computer programming expertise to develop software systems that meet user needs. The terms ''programmer'' and ''coder'' overlap ''software engineer'', but they imply only the construction aspect of a typical software engineer workload. A software engineer applies a software development process, which involves defining, Implementation, implementing, Software testing, testing, Project management, managing, and Software maintenance, maintaining software systems, as well as developing the software development process itself. History Beginning in the 1960s, software engineering was recognized as a separate field of engineering. The development of software engineering was seen as a struggle. Problems included software that was over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instruction Path Length
In computer performance, the instruction path length is the number of machine code instructions required to execute a section of a computer program. The total path length for the entire program could be deemed a measure of the algorithm's performance on a particular computer hardware. The path length of a simple conditional instruction would normally be considered as equal to 2, one instruction to perform the comparison and another to take a branch if the particular condition is satisfied. The length of time to execute each instruction is not normally considered in determining path length and so path length is merely an indication of relative performance rather than in any sense absolute. When executing a benchmark program, most of the instruction path length is typically inside the program's inner loop. Before the introduction of caches, the path length was an approximation of running time, but in modern CPUs with caches, it can be a much worse approximation, with some load ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Call Graph
A call graph (also known as a call multigraph) is a control-flow graph, which represents calling relationships between subroutines in a computer program. Each node represents a procedure and each edge ''(f, g)'' indicates that procedure ''f'' calls procedure ''g''. Thus, a cycle in the graph indicates recursive procedure calls. Basic concepts Call graphs can be dynamic or static. A dynamic call graph is a record of an execution of the program, for example as output by a profiler. Thus, a dynamic call graph can be exact, but only describes one run of the program. A static call graph is a call graph intended to represent every possible run of the program. The exact static call graph is an undecidable problem, so static call graph algorithms are generally overapproximations. That is, every call relationship that occurs is represented in the graph, and possibly also some call relationships that would never occur in actual runs of the program. Call graphs can be defined to repre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instruction Set Simulator
An instruction set simulator (ISS) is a simulation model (abstract), model, usually coded in a high-level programming language, which mimics the behavior of a mainframe or microprocessor by "reading" instructions and maintaining internal variables which represent the processor's Processor register, registers. Instruction simulation is a methodology employed for one of several possible reasons: * To simulate the instruction set architecture (ISA) of a future processor to allow software development and test to proceed without waiting for the development and production of the hardware to finish. This is often known as "shift-left" or "pre-silicon support" in the hardware development field. A full system simulator or virtual platform for the future hardware typically includes one or more instruction set simulators. * To simulate the machine code of another hardware device or entire computer for upward Compatibility mode (software), compatibility. :: For example, the IBM 1401 was simu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sampling (statistics)
In this statistics, quality assurance, and survey methodology, sampling is the selection of a subset or a statistical sample (termed sample for short) of individuals from within a population (statistics), statistical population to estimate characteristics of the whole population. The subset is meant to reflect the whole population, and statisticians attempt to collect samples that are representative of the population. Sampling has lower costs and faster data collection compared to recording data from the entire population (in many cases, collecting the whole population is impossible, like getting sizes of all stars in the universe), and thus, it can provide insights in cases where it is infeasible to measure an entire population. Each observation measures one or more properties (such as weight, location, colour or mass) of independent objects or individuals. In survey sampling, weights can be applied to the data to adjust for the sample design, particularly in stratified samplin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Program Status Word
The program status word (PSW) is a register that performs the function of a status register and program counter, and sometimes more. The term is also applied to a copy of the PSW in storage. This article only discusses the PSW in the IBM System/360 and its successors, and follows the IBM convention of numbering bits starting with 0 as the leftmost (most significant) bit. Although certain fields within the PSW may be tested or set by using non-privileged instructions, testing or setting the remaining fields may only be accomplished by using privileged instructions. Contained within the PSW are the two bit condition code, representing zero, positive, negative, overflow, and similar flags of other architectures' status register A status register, flag register, or condition code register (CCR) is a collection of status Flag (computing), flag bits for a Central processing unit, processor. Examples of such registers include FLAGS register (computing), FLAGS register in the ...s. C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM/370
The IBM System/370 (S/370) is a range of IBM mainframe computers announced as the successors to the System/360 family on June 30, 1970. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path for customers; this, plus improved performance, were the dominant themes of the product announcement. Early 370 systems differed from the 360 largely in their internal circuitry, moving from the Solid Logic Technology hybrid integrated circuits containing separate transistors to more modern monolithic integrated circuits containing multiple transistors per integrated circuit, which IBM referred to as Monolithic System Technology, or MST. The higher density packaging allowed several formerly optional features from the 360 line to be included as standard features of the machines, floating-point support for instance. The 370 also added a small number of new instructions. At the time of its introduction, the development of virtual memory systems ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM/360
The IBM System/360 (S/360) is a family of mainframe computer systems announced by IBM on April 7, 1964, and delivered between 1965 and 1978. System/360 was the first family of computers designed to cover both commercial and scientific applications and a complete range of applications from small to large. The design distinguished between computer architecture, architecture and implementation, allowing IBM to release a suite of compatible designs at different prices. All but the only partially compatible IBM System/360 Model 44, Model 44 and the most expensive systems use microcode to implement the instruction set, featuring 8-bit computing, 8-bit byte addressing and fixed-point binary, fixed-point decimal and IBM hexadecimal floating-point, hexadecimal floating-point arithmetic, floating-point calculations. The System/360 family introduced IBM's Solid Logic Technology (SLT), which packed more transistors onto a circuit card, allowing more powerful but smaller computers. System/36 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed Computing
Distributed computing is a field of computer science that studies distributed systems, defined as computer systems whose inter-communicating components are located on different networked computers. The components of a distributed system communicate and coordinate their actions by passing messages to one another in order to achieve a common goal. Three significant challenges of distributed systems are: maintaining concurrency of components, overcoming the lack of a global clock, and managing the independent failure of components. When a component of one system fails, the entire system does not fail. Examples of distributed systems vary from SOA-based systems to microservices to massively multiplayer online games to peer-to-peer applications. Distributed systems cost significantly more than monolithic architectures, primarily due to increased needs for additional hardware, servers, gateways, firewalls, new subnets, proxies, and so on. Also, distributed systems are prone to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transaction Processing
In computer science, transaction processing is information processing that is divided into individual, indivisible operations called ''transactions''. Each transaction must succeed or fail as a complete unit; it can never be only partially complete. For example, when you purchase a book from an online bookstore, you exchange money (in the form of credit) for a book. If your credit is good, a series of related operations ensures that you get the book and the bookstore gets your money. However, if a single operation in the series fails during the exchange, the entire exchange fails. You do not get the book and the bookstore does not get your money. The technology responsible for making the exchange balanced and predictable is called ''transaction processing''. Transactions ensure that data-oriented resources are not permanently updated unless all operations within the transactional unit complete successfully. By combining a set of related operations into a unit that either com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Application Performance Management
In the fields of information technology and systems management, application performance management (APM) is the monitoring and management of the performance and availability of software applications. APM strives to detect and diagnose complex application performance problems to maintain an expected level of service. APM is "the translation of IT metrics into business meaning ( .e.value)." Measuring application performance Two sets of performance metrics are closely monitored. The first set of performance metrics defines the performance experienced by end-users of the application. One example of performance is average response times under peak load. The components of the set include load and response times: :* The load is the volume of transactions processed by the application, e.g., transactions per second, requests per second, pages per second. Without being loaded by computer-based demands (e.g. searches, calculations, transmissions), most applications are fast enough, whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Krauss Matching Wildcards Algorithm
In computer science, the Krauss wildcard-matching algorithm is a pattern matching algorithm. Based on the wildcard syntax in common use, e.g. in the Microsoft Windows command-line interface, the algorithm provides a non- recursive mechanism for matching patterns in software applications, based on syntax simpler than that typically offered by regular expressions. History The algorithm is based on a history of development, correctness and performance testing, and programmer feedback that began with an unsuccessful search for a reliable non-recursive algorithm for matching wildcards. An initial algorithm, implemented in a single while loop, quickly prompted comments from software developers, leading to improvements. Ongoing comments and suggestions culminated in a revised algorithm still implemented in a single while loop but refined based on a collection of test cases and a performance profiler. The experience tuning the single while loop using the profiler prompted development of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
