GNU Hurd is the multiserver microkernel written as part of GNU. It has been under development since 1990 by the GNU Project of the Free Software Foundation, designed as a replacement for the Unix kernel, and released as free software under the GNU General Public License. When the Linux kernel proved to be a viable solution, development of GNU Hurd slowed, at times having slipped intermittently between stasis and renewed activity and interest.
The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines the application programming interface (API), along with command line shells and utility interfaces, for software compatibility with variants of Unix and other operating systems.
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, but in most cases a thread is a component of a process. Multiple threads can exist within one process, executing concurrently and 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.
QNX is a commercial Unix-like real-time operating system, aimed primarily at the embedded systems market. QNX was one of the first commercially successful microkernel operating systems. As of 2020, it is used in a variety of devices including cars and mobile phones.
In computing, a system call is the programmatic way in which a computer program requests a service from the kernel of the operating system on which it is executed. This may include hardware-related services, creation and execution of new processes, and communication with integral kernel services such as process scheduling. System calls provide an essential interface between a process and the operating system.
The GNU Project is a free software, mass collaboration project that Richard Stallman announced on September 27, 1983. Its goal is to give computer users freedom and control in their use of their computers and computing devices by collaboratively developing and publishing software that gives everyone the rights to freely run the software, copy and distribute it, study it, and modify it. GNU software grants these rights in its license.
The GNU C Library, commonly known as glibc, is the GNU Project's implementation of the C standard library. Despite its name, it now also directly supports C++. It was started in the early 1990s by the Free Software Foundation (FSF) for their GNU operating system.
The Native POSIX Thread Library (NPTL) is an implementation of the POSIX Threads specification for the Linux operating system.
The Linux kernel provides several interfaces to user-space applications that are used for different purposes and that have different properties by design. There are two types of application programming interface (API) in the Linux kernel that are not to be confused: the "kernel–user space" API and the "kernel internal" API.
In computer operating systems, a light-weight process (LWP) is a means of achieving multitasking. In the traditional meaning of the term, as used in Unix System V and Solaris, a LWP runs in user space on top of a single kernel thread and shares its address space and system resources with other LWPs within the same process. Multiple user-level threads, managed by a thread library, can be placed on top of one or many LWPs - allowing multitasking to be done at the user level, which can have some performance benefits.
TRIX is a network-oriented research operating system developed in the late 1970s at MIT's Laboratory for Computer Science (LCS) by Professor Steve Ward and his research group. It ran on the NuMachine and had remote procedure call functionality built into its kernel, but was otherwise a Version 7 Unix workalike.
In computer science, a fiber is a particularly lightweight thread of execution.
CPU time is the amount of time for which a central processing unit (CPU) was used for processing instructions of a computer program or operating system, as opposed to elapsed time, which includes for example, waiting for input/output (I/O) operations or entering low-power (idle) mode. The CPU time is measured in clock ticks or seconds. Often, it is useful to measure CPU time as a percentage of the CPU's capacity, which is called the CPU usage.
Java Native Access (JNA) is a community-developed library that provides Java programs easy access to native shared libraries without using the Java Native Interface. JNA's design aims to provide native access in a natural way with a minimum of effort. No boilerplate or generated glue code is required.
The Linux kernel, developed by contributors worldwide, is a free and open-source, monolithic, modular, Unix-like operating system kernel, and it is highly configurable by the users who've been granted the necessary privileges.
Unix is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, development starting in the 1970s at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others.
In computing the Process Environment Block is a data structure in the Windows NT operating system family. It is an opaque data structure that is used by the operating system internally, most of whose fields are not intended for use by anything other than the operating system. Microsoft notes, in its MSDN Library documentation — which documents only a few of the fields — that the structure "may be altered in future versions of Windows". The PEB contains data structures that apply across a whole process, including global context, startup parameters, data structures for the program image loader, the program image base address, and synchronization objects used to provide mutual exclusion for process-wide data structures.
Bionic is an implementation of the standard C library, developed by Google for its Android operating system. It differs from the GNU C Library (glibc) in being designed for devices with less memory and processor power than a typical Linux system. It is also released under a BSD license, rather than the GNU Lesser General Public License used for glibc. This difference was important in the early days of Android, when static linking was common, and is still helpful in introducing Android to software companies used to proprietary operating systems, who can be wary of the LGPL, and unclear about the differences between it and the full GPL.
In computer science, shared memory is memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies. Shared memory is an efficient means of passing data between programs. Depending on context, programs may run on a single processor or on multiple separate processors.
