Hardware support for real-time operating systems

Abstract

The growing complexity of embedded applications and pressure on time-to-market has resulted in the increasing use of embedded real-time operating systems. Unfortunately, RTOSes can introduce a significant performance degradation. This paper presents the Real-Time Task Manager (RTM)-a processor extension that minimizes the performance drawbacks associated with RTOSes. The RTM accomplishes this by supporting, in hardware, a few of the common RTOS operations that are performance bottlenecks: task scheduling, time management, and event management. By exploiting the inherent parallelism of these operations, the RTM completes them in constant time, thereby significantly reducing RTOS overhead. It decreases both the processor time used by the RTOS and the maximum response time by an order of magnitude.

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“…The nano-processor provides upgradability, flexibility and also enhancing the execution time by moving selected inefficient OS services in hardware to save on power consumption to a great extent as shown in several studies. Leveraging the potential of hardware parallelism, Paul Kohot et al in [38], developed Real-Time Manager (RTM). Routine housekeeping tasks are implemented in hardware and thus relieve the processor for critical functions which boosts the overall performance.…”

“…et al is Hardware implemented Real-Time Operating System) in [50] is designed to be very flexible and support most of the features normally found in a standard software RTOS directly in hardware without sacrificing flexibility. HartOS has been compared to the commercial Sierra kernel, its performance outperforms that of the Sierra Kernel [51]. The HartOS the ability to let the kernel run at a higher clock frequency than the microprocessor, which allows more tasks to be processed serially at the same tick frequency, and speed up the part of the API functions executed in the kernel.…”

Hardware architecture support for mixed criticality and real-time systems

“…Several architectures [4,17,72,42,27,40] have been proposed to improve the performance of schedulers using hardware accelerators. Most schedulers implement some kind of priority based scheduling algorithm that requires a priority queue to sort the tasks based on their priority.…”

“…A hardware scheduler for multiprocessor system on chip is presented in [27], which implements the Pfair scheduling algorithm. A real time task manager (RTM) that implements scheduling, time management, and event management in hardware is presented in [40]. The RTM supports static priority-based scheduling and is implemented as an on-chip peripheral that communicates with the processor though a memory mapped interface.…”

Software/hardware RTOS and system overhead in a hard real-time environment

“…The Real-Time Task Manager (RTM) [5] provides hardware support for a software RTOS by implementing three time consuming RTOS functionalities: task scheduling, time management and event management. A performance test is done using RTM and a simulator of the Texas Instruments TMS320C6201 with nC/OS-II and NOS (custom nonpreemptive) RTOSs.…”