RTOS Vs GPOS  -What to choose for Embedded Applications

RTOS vs GPOS what to choose for embedded applications

What is RTOS?

Operating system with stringent time constrain & expectations to deliver a predictable response to applications is generally referred to as a real-time operating system. This OS can run both on general and specific hardware that is designed.

Ex: robotics

RTOS is a high performance, cost-effective OS suited for executing multi operations at the same time with the same resources. RTOS can be easily integrated into microcontroller as they have small memory footprints. Further, as foresaid they multitask, parallelly execute by switching between executing tasks.

Types of RTOS

There are two types of RTOS out there

i. Hard Real Time Systems

ii. Soft Real Time Systems

i. Hard Real Time Systems

HRTS is a purely deterministic and time constraint system. They process/ complete the assigned task exactly on the time specified. There is no prior (or) post-processing/ completion of the task.

Ex: avionics, pacemakers, and defense applications.

ii. Soft Real Time Systems

In SRTS there is no such thing as meeting the deadlines every time for every task, provided they should process and give the results every time. On the contrary, they must also not miss deadlines. Missing the deadline for every time will worsen the performance of the system thus cannot be used by users.

Ex: audio player, video player, and PC

What is GPOS?

OS that allows the user to access various applications & interfaces is called as GPOS. These are generally found in common systems, desktops that run applications.

Ex: windows 10

Difference between RTOS & GPOS

  • Hardware Architecture

GPOS are used in heavy architectures (ie) GPOS are generally used to add another process accordingly to do more tasks. They are usually found on PC, laptops, and servers. For example, the user can add an extra application like IDE, software for games, players, etc., GPOS requires a minimum of 64Mb of RAM, high-end microcontroller (or) microprocessor as CPU for functioning.

In antipodal RTOS are used for lightweight architecture systems such as mobile phones, ATM, chocolate vending machines, etc., They are fixed, are specifically used to do a limited number of tasks. RTOS requires minuscule kilobyte of RAM, microcontroller as CPU for performing assigned tasks.

  • Interrupt Latency

GPOS definitely suffers from latency issues. The more number of tasks, threads to schedule, the more is the latency (more interrupt latency as process time is more). RTOS does not suffer from such issues. They have bounded latency meaning task assigned will be executed within a predetermined time (Zero interrupt latency as process time is less)

  • Kernel

RTOS uses a proactive kernel whereas GPOS uses reactive kernel. Proactive kernel process the threads with higher priority initially (ie) it puts all other processes with lesser priority as the external process. Whereas GPOS (or) reactive kernel does the vice versa (ie) it processes the threads in first come first serve fashion meaning higher priority process should wait until the existing process is completed.

  • Task Scheduling

Scheduling is the method that provides resources to be processed by the system. Alike kernel task scheduling in RTOS is carried out based on priority. Task scheduler algorithm of RTOS schedules the task in such a way that higher priority tasks are scheduled first and low priority process is paused until higher priority tasks are processed completely.

On the other hand GPOS, scheduling is not based on priority. As aforementioned even when a high priority task comes for processing it has to wait until the existing process is completed.RTOS has low throughput as per proactive scheduling. Whereas, GPOS task scheduler algorithm is programmed in such a way to achieve high throughput. High throughput here refers to the total number of tasks processed & executed per unit time.

  • Deterministic

A deterministic system is one that does not have any randomness in it. With constant usage of a deterministic system, it is easy for one to predict the output for the given input. RTOS being a deterministic system it is easy to predict the output of different inputs but not the time taken for the processing and execution.Howbeit, GPOS being non-deterministic (has more randomness) it is not easy to predict the output but the time taken to process different inputs can be predicted.

Reasons why RTOS remains to be an infallible choice for embedded applications

The market expectations of embedded systems keep magnifying so is the hype for RTOS. By and large scheduling, software timers, queuing mechanism, low memory footprint, etc., are some reasons why RTOS still remains to be a discrete choice for embedded product development.Moreover, concepts like virtual mapping, paging, & huge file system management are still not available in RTOS thus making them a more economically cost-effective choice for embedded software applications.

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