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In particular, the POSIX specification and the Linux man page signal (7) require that all system functions directly or indirectly called from a signal function are async-signal safe. [ 6 ] [ 7 ] The signal-safety(7) man page gives a list of such async-signal safe system functions (practically the system calls ), otherwise it is an undefined ...
Interrupt handlers have a multitude of functions, which vary based on what triggered the interrupt and the speed at which the interrupt handler completes its task. For example, pressing a key on a computer keyboard , [ 1 ] or moving the mouse , triggers interrupts that call interrupt handlers which read the key, or the mouse's position, and ...
In computing, a keyboard controller is a device that interfaces a keyboard to a computer. Its main function is to inform the computer when a key is pressed or released. When data from the keyboard arrives, the controller raises an interrupt (a keyboard interrupt) to allow the CPU to handle the input.
Busy-waiting itself can be made much less wasteful by using a delay function (e.g., sleep()) found in most operating systems. This puts a thread to sleep for a specified time, during which the thread will waste no CPU time. If the loop is checking something simple then it will spend most of its time asleep and will waste very little CPU time.
A user thread either runs at user-kernel priority (when it is actually running in the kernel, e.g. running a syscall on behalf of userland), or a user thread runs at user priority. DragonFly does preempt, it just does it very carefully and only under particular circumstances. An LWKT interrupt thread can preempt most other threads, for example ...
But if the function is used in a reentrant interrupt handler and a second interrupt arises while the mutex is locked, the second routine will hang forever. As interrupt servicing can disable other interrupts, the whole system could suffer. The same function can be implemented to be both thread-safe and reentrant using the lock-free atomics in ...
In computing, keyboard interrupt may refer to: A special case of signal (computing) , a condition (often implemented as an exception) usually generated by the keyboard in the text user interface A hardware interrupt generated when a key is pressed or released, see keyboard controller (computing)
Another feature is a semi-asynchronous mechanism that raises an asynchronous exception only during certain operations of the program. For example, Java's Thread. interrupt only affects the thread when the thread calls an operation that throws InterruptedException. [53]