Sunday, January 10, 2016

RTOS

RTOS

A real-time operating system (RTOS) is an operating system (OS) intended to serve real-time application process data as it comes in, typically without buffering delays. Processing time requirements (including any OS delay) are measured in tenths of seconds or shorter.

A key characteristic of an RTOS is the level of its consistency concerning the amount of time it takes to accept and complete an application's task; the variability is jitter. A hard real-time operating system has less jitter than a soft real-time operating system. The chief design goal is not high throughput, but rather a guarantee of a soft or hard performance category. An RTOS that can usually or generally meet a deadline is a soft real-time OS, but if it can meet a deadline deterministically it is a hard real-time OS.

An RTOS has an advanced algorithm for scheduling. Scheduler flexibility enables a wider, computer-system orchestration of process priorities, but a real-time OS is more frequently dedicated to a narrow set of applications. Key factors in a real-time OS are minimal interrupt latency and minimal thread switching latency; a real-time OS is valued more for how quickly or how predictably it can respond than for the amount of work it can perform in a given period of time. [more info]


According to a 2014 Embedded Market Study, the following RTOSes are among the top 10 operating systems used in the embedded systems market:

  • Green Hills Software INTEGRITY
  • Wind River VxWorks
  • QNX Neutrino
  • FreeRTOS
  • Micrium µC/OS-II, III
  • Windows CE
  • TI-RTOS Kernel (previously called DSP/BIOS)
  • RTEMS open source RTOS designed for embedded systems, mainly used for missile and space probes control

 








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