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Protothread
A protothread is a low-overhead mechanism for concurrent programming. Protothreads function as stackless, lightweight threads, or coroutines, providing a blocking context cheaply using minimal memory per protothread (on the order of single bytes). Protothreads are used to accomplish a non-preempted form of concurrency known as cooperative multitasking and, therefore, do not incur context switch when yielding to another thread. Within a protothread, yielding is accomplished by utilizing Duff's device within a thread's function and an external variable used in within the switch statement. This allows jumping (resuming) from a yield upon another function call. In order to block threads, these yields may be guarded by a conditional so that successive calls to the same function will yield unless the guard conditional is true. A feature of protothreads relative to other implementations of coroutines, or proper threads, is that they are stackless. This has advantages and disadvantages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contiki
Contiki is an operating system for networked, memory-constrained systems with a focus on low-power wireless Internet of Things (IoT) devices. Extant uses for Contiki include systems for street lighting, sound monitoring for smart cities, radiation monitoring, and alarms.. It is open-source software released under the BSD-3-Clause license. Contiki was created by Adam Dunkels in 2002 and has been further developed by a worldwide team of developers from Texas Instruments, Atmel, Cisco, ENEA, ETH Zurich, Redwire, RWTH Aachen University, Oxford University, SAP, Sensinode, Swedish Institute of Computer Science, ST Microelectronics, Zolertia, and many others. Contiki gained popularity because of its built in TCP/IP stack and lightweight preemptive scheduling over event-driven kernel which is a very motivating feature for IoT. The name ''Contiki'' comes from Thor Heyerdahl's famous Kon-Tiki raft. Contiki provides multitasking and a built-in Internet Protocol Suite (TCP/IP stack), yet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coroutines
Coroutines are computer program components that generalize subroutines for non-preemptive multitasking, by allowing execution to be suspended and resumed. Coroutines are well-suited for implementing familiar program components such as cooperative tasks, exceptions, event loops, iterators, infinite lists and pipes. Melvin Conway coined the term ''coroutine'' in 1958 when he applied it to the construction of an assembly program. The first published explanation of the coroutine appeared later, in 1963. Comparison with Subroutines Subroutines are special cases of coroutines. When subroutines are invoked, execution begins at the start, and once a subroutine exits, it is finished; an instance of a subroutine only returns once, and does not hold state between invocations. By contrast, coroutines can exit by calling other coroutines, which may later return to the point where they were invoked in the original coroutine; from the coroutine's point of view, it is not exiting but calling a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coroutine
Coroutines are computer program components that generalize subroutines for non-preemptive multitasking, by allowing execution to be suspended and resumed. Coroutines are well-suited for implementing familiar program components such as cooperative tasks, exceptions, event loops, iterators, infinite lists and pipes. Melvin Conway coined the term ''coroutine'' in 1958 when he applied it to the construction of an assembly program. The first published explanation of the coroutine appeared later, in 1963. Comparison with Subroutines Subroutines are special cases of coroutines. When subroutines are invoked, execution begins at the start, and once a subroutine exits, it is finished; an instance of a subroutine only returns once, and does not hold state between invocations. By contrast, coroutines can exit by calling other coroutines, which may later return to the point where they were invoked in the original coroutine; from the coroutine's point of view, it is not exiting but calling a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duff's Device
In the C programming language, Duff's device is a way of manually implementing loop unrolling by interleaving two syntactic constructs of C: the - loop and a switch statement. Its discovery is credited to Tom Duff in November 1983, when Duff was working for Lucasfilm and used it to speed up a real-time animation program. Loop unrolling attempts to reduce the overhead of conditional branching needed to check whether a loop is done, by executing a batch of loop bodies per iteration. To handle cases where the number of iterations is not divisible by the unrolled-loop increments, a common technique among assembly language programmers is to jump directly into the middle of the unrolled loop body to handle the remainder. Duff implemented this technique in C by using C's case label fall-through feature to jump into the unrolled body. Original version Duff's problem was to copy 16-bit unsigned integers ("shorts" in most C implementations) from an array into a memory-mapped output regist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adam Dunkels
Adam Dunkels (born 1978) is a Swedish computer scientist, computer programmer, entrepreneur, and founder of Thingsquare, an Internet of things (IoT) product development business. His father was professor of mathematics Andrejs Dunkels. His mother was professor Kerstin Vännman. His work is mainly focused on computer networking technology and distributed communication for small embedded systems and devices and wireless sensor networks on the Internet. He attended the Swedish Institute of Computer Science where he earned Bachelor of Science (B.S.), Master of Science (M.S.) in 2001, and a Doctor of Philosophy (Ph.D.) in 2007. Dunkels is best known to the embedded community as the author of the uIP (micro-IP) and lwIP TCP/IP Internet protocol suite (stacks). He invented protothreads and the operating system Contiki. The ''MIT Technology Review'' placed him on the TR35 list of world's top 35 innovators under 35, in 2009. His book ''Interconnecting Smart Objects with IP: the Next Int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thread (computer Science)
In computer science, a thread of execution is the smallest sequence of programmed instructions that can be managed independently by a scheduler, which is typically a part of the operating system. The implementation of threads and processes differs between operating systems. In Modern Operating Systems, Tanenbaum shows that many distinct models of process organization are possible.TANENBAUM, Andrew S. Modern Operating Systems. 1992. Prentice-Hall International Editions, ISBN 0-13-595752-4. In many cases, a thread is a component of a process. The multiple threads of a given process may be executed concurrently (via multithreading capabilities), sharing resources such as memory, while different processes do not share these resources. In particular, the threads of a process share its executable code and the values of its dynamically allocated variables and non- thread-local global variables at any given time. History Threads made an early appearance under the name of "tasks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microthread
Microthreads are functions that may run in parallel to gain increased performance in microprocessors. They provide an execution model that uses a few additional instructions in a conventional processor to break code down into fragments that execute simultaneously. Dependencies are managed by making registers in the microprocessors executing the code synchronising, so one microthread will wait for another to produce data. This is a form of dataflow. This model can be applied to an existing instruction set architecture incrementally by providing just five new instructions to implement concurrency controls. A ''set'' of microthreads is a static partition of a basic block into concurrently executing fragments, which execute on a single processor and share a microcontext. An ''iterator'' over a set provides a dynamic and parametric family of microthreads. Iterators capture loop concurrency and can be scheduled to different processors. An iterator over a set is created dynamically and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concurrent Programming
Concurrent means happening at the same time. Concurrency, concurrent, or concurrence may refer to: Law * Concurrence, in jurisprudence, the need to prove both ''actus reus'' and ''mens rea'' * Concurring opinion (also called a "concurrence"), a legal opinion which supports the conclusion, though not always the reasoning, of the majority. * Concurrent estate, a concept in property law * Concurrent resolution, a legislative measure passed by both chambers of the United States Congress * Concurrent sentences, in criminal law, periods of imprisonment that are served simultaneously Computing * Concurrency (computer science), the property of program, algorithm, or problem decomposition into order-independent or partially-ordered units * Concurrent computing, the overlapping execution of multiple interacting computational tasks * Concurrence (quantum computing), a measure used in quantum information theory * Concurrent Computer Corporation, an American computer systems manufacturer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
POSIX Threads
POSIX Threads, commonly known as pthreads, is an execution model that exists independently from a language, as well as a parallel execution model. It allows a program to control multiple different flows of work that overlap in time. Each flow of work is referred to as a '' thread'', and creation and control over these flows is achieved by making calls to the POSIX Threads API. POSIX Threads is an API defined by the standard ''POSIX.1c, Threads extensions (IEEE Std 1003.1c-1995)''. Implementations of the API are available on many Unix-like POSIX-conformant operating systems such as FreeBSD, NetBSD, OpenBSD, Linux, macOS, Android, Solaris, Redox, and AUTOSAR Adaptive, typically bundled as a library libpthread. DR-DOS and Microsoft Windows implementations also exist: within the SFU/SUA subsystem which provides a native implementation of a number of POSIX APIs, and also within third-party packages such as ''pthreads-w32'', which implements pthreads on top of existing Windows API. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNIX Kernel
A Unix architecture is a computer operating system system architecture that embodies the Unix philosophy. It may adhere to standards such as the Single UNIX Specification (SUS) or similar POSIX IEEE standard. No single published standard describes all Unix architecture computer operating systems — this is in part a legacy of the Unix wars. Description There are many systems which are Unix-like in their architecture. Notable among these are the Linux distributions. The distinctions between Unix and Unix-like systems have been the subject of heated legal battles, and the holders of the UNIX brand, The Open Group, object to "Unix-like" and similar terms. For distinctions between SUS branded UNIX architectures and other similar architectures, see Unix-like. Kernel A Unix kernel — the core or key components of the operating system — consists of many kernel subsystems like process management, scheduling, file management, device management, network management, memory m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scheduling (computing)
In computing, scheduling is the action of assigning ''resources'' to perform ''tasks''. The ''resources'' may be processors, network links or expansion cards. The ''tasks'' may be threads, processes or data flows. The scheduling activity is carried out by a process called scheduler. Schedulers are often designed so as to keep all computer resources busy (as in load balancing), allow multiple users to share system resources effectively, or to achieve a target quality-of-service. Scheduling is fundamental to computation itself, and an intrinsic part of the execution model of a computer system; the concept of scheduling makes it possible to have computer multitasking with a single central processing unit (CPU). Goals A scheduler may aim at one or more goals, for example: * maximizing ''throughput'' (the total amount of work completed per time unit); * minimizing '' wait time'' (time from work becoming ready until the first point it begins execution); * minimizing '' latency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GNU Compiler Collection
The GNU Compiler Collection (GCC) is an optimizing compiler produced by the GNU Project supporting various programming languages, hardware architectures and operating systems. The Free Software Foundation (FSF) distributes GCC as free software under the GNU General Public License (GNU GPL). GCC is a key component of the GNU toolchain and the standard compiler for most projects related to GNU and the Linux kernel. With roughly 15 million lines of code in 2019, GCC is one of the biggest free programs in existence. It has played an important role in the growth of free software, as both a tool and an example. When it was first released in 1987 by Richard Stallman, GCC 1.0 was named the GNU C Compiler since it only handled the C programming language. It was extended to compile C++ in December of that year. Front ends were later developed for Objective-C, Objective-C++, Fortran, Ada, D and Go, among others. The OpenMP and OpenACC specifications are also supported in the C and C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
