Virtual Machines and Real-time OS (RTOS)
- (Photo: Princeton University, Office of Communications)
- Overview
Virtual Machines (VMs) and Real-time Operating Systems (RTOS) serve distinct purposes in computing, with VMs focusing on creating isolated software environments and RTOS prioritizing deterministic timing for critical applications.
While VMs can be used to test or simulate real-time systems, they are generally not suitable for production environments due to the potential for unpredictable performance overhead from the host OS.
Virtual Machines (VMs):
- Function: VMs create software-based versions of a computer, allowing multiple operating systems to run concurrently on a single physical machine.
- Purpose: They are used for resource optimization, application isolation, software testing, and development in a sandboxed environment.
- Limitations: VMs introduce overhead, making them unsuitable for hard real-time applications where strict timing is crucial, according to a Quora post.
Real-time Operating Systems (RTOS):
- Function: RTOS are designed for applications requiring predictable and deterministic timing, often measured in microseconds or milliseconds.
- Purpose: They are used in embedded systems, industrial automation, aerospace, and other applications where missed deadlines can lead to system failure.
- Features: RTOS include features like priority-based scheduling, fast context switching, and rigorous resource management to meet strict timing requirements.
Key Differences:
- Timing Determinism: RTOS guarantee timely execution, while VMs introduce potential performance variability.
- Application Focus: RTOS are designed for time-critical applications, while VMs are used for broader tasks like software testing and resource management.
- Overhead: VMs introduce overhead due to virtualization, which can be problematic for real-time systems.
- Virtual Machine: A Virtual Computer Within A Computer
A virtual machine, often referred to simply as a VM, is no different from any other physical computer such as a laptop, smartphone, or server. It has a CPU, memory, disks to store files, and can connect to the Internet when needed.
While the components that make up a computer (called hardware) are physical and tangible, a VM is often thought of as a virtual or software-defined computer in a physical server that exists only as code.
Virtualization is the process of creating a software-based or "virtual" version of a computer with data from a physical host (such as your personal computer) and/or a remote server - such as a server in a cloud provider's data center.
A virtual machine is a computer file, often called an image, that behaves like an actual computer. It can run in a window as a separate computing environment, often running a different operating system - or even as a user's entire computer experience - which is common on many people's work computers.
The virtual machine is separate from the rest of the system, which means that the software inside the virtual machine cannot interfere with the host's main operating system.
- Cloud Virtualization
Cloud virtualization is an important aspect of cloud systems that helps in the efficient delivery of cloud computing services. Deploying virtual computing resources in the cloud, emulating the functionality of physical computing resources, acts as a flexible load balancing management tool that allows for rapid adjustment of computing services delivered on demand.
Virtualization technology provides enterprises with a tool that can improve the high availability, scalability, and reliability of cloud systems or cloud computing technologies, which can be accessed by enterprises to meet their information technology needs. Virtualization is also a very important component of cloud computing technology for disaster recovery and failover support.
Virtualization in cloud computing is building a virtual platform consisting of server operating systems and storage devices. This helps users by providing multiple machines at the same time while allowing multiple users to share a single physical resource instance or application.
Cloud virtualization also manages workloads by transforming traditional computing to make it more scalable, economical, and efficient. Virtualization in cloud computing is rapidly consolidating the basic way of computing.
An important feature of virtualization is that it allows multiple customers and companies to share applications. Cloud computing can also be understood as the delivery of services and applications in a virtualized environment. This environment can be either public or private.
With virtualization, customers can maximize resource utilization and reduce the number of physical systems required.
- Real-time Operating Systems
A real-time operating system (RTOS) must be fast and responsive, schedule tasks and manage limited resources, and ensure functions are isolated and free of interference from other functions.
The main responsibility of an operating system is to manage hardware resources and activities in the system: scheduling application programs, writing files to disk, sending data across a network, and so on. When the OS must handle multiple events concurrently and ensure that the system responds to those events within predictable time limits
A real-time operating system (RTOS) is an operating system (OS) intended to serve real-time applications that process data as it comes in, typically without buffer delays. Processing time requirements (including any OS delay) are measured in tenths of seconds or shorter increments of time.
A real-time system is a time-bound system which has well-defined, fixed time constraints. Processing must be done within the defined constraints or the system will fail. They either are event-driven or time-sharing.
Event-driven systems switch between tasks based on their priorities, while time-sharing systems switch the task based on clock interrupts.
Most RTOSs use a pre-emptive scheduling algorithm.
[More to come ...]
