Purpose of an Interrupt Vector, Virtualization and Simulation - Assignment Example

1) Define the concepts interrupt and trap, and explain the purpose of an interrupt vector. An interrupt is a command signal generated by an electronic device that is attached to the computer that acts as a signal for the operating systems to tell it what to do. While changing from one task to another the CPU follows a procedure called the context switch to prevent the tasks from conflicting with each other. When an interrupt is generated, OS saves the current execution state by means of context switch. After saving the execution state, the OS executes the interrupt handler at the interrupt vector. Kind of interrupt that is generated by software in response of an exception or an explicit trap instruction is called a trap. (e.g. for a system call). This mechanism is used to prevent programming mistakes with system resources. It also shares common system resources in an appropriate manner under OS control. It prevents accessibility to protected memory segments. It also identifies instructions that can cause error conditions and inconsistent system state. Memory location of interrupt handler that signifies interrupts and also will save them in a queue if multiple interrupts are in processing, is called interrupt vector. The interrupt vector is a matrix of pointers to specific interrupt-handling routines. 2) What role do device controllers and device drivers play in a computer system? A hardware part that is called the device controller along with any device makes up the computer system. The device controllers basically acts as an interface between the device and the OS of that computer. Device controllers is also responsible of transferring data from other devices that controls it and the local buffers. To store and execute necessary commands in device controller, registers and buffers are integrated in the device controller. To provide interface between a device controller and OS, there is a device driver in OS that presents a steady interface into the device. First the device driver is introduced in to the OS to which the device is to be connected and then User and the system can exchange data with help of device through the device itself. 3) Explain cache coherency. In multiprocessor, two copies of the same data may reside in the local cache of each CPU. If one of the CPU changes the data, the Caches of the other cache coherency includes. Storing the data in multiple caches signifies one of the best ways of storing data. In this kind of shared memory, there is different cache memory for each of the processors. It is possible that many copies of one direction operand would exist on multiple caches that would exist on different processors. If one copy is changed, all the copies that are present on the other caches must also be changed. Cache coherency is the process that ensures these adjustments. 4) Describe why multi-core processing is more efficient than placing each processor on its own chip. The relatively more efficient communication between the processors on the same chip as compared to that on processors on different chips make the process more efficient. The processors present on different chips make the process much more slower. Multi-core processors also ensure power consumption, better performance and also better simulation of multiple simultaneous processing of different tasks. Through the divide and conquer strategy, multi core processors ensures the better dealing of processes as multiple processes can be completed simultaneously. In dual core setup, the two processors are attached to the same socket making the connection faster. It is comparable to the different processors installed on the same computer when we talk in terms of functionalities. 5) Explain why a modular kernel may be the best of the current operating system design techniques. For a modular design, the kernel has the ability to perform the necessary operations and knows how to communicate between different modules. It combines the plus points of both layered and microkernel designs. If more functionality is the requirement, more modules can be loaded dynamically into the kernel by the user. This would enhance the working of the operating system thus increasing the performance of the operating system. A kernel has protected interferences which is also well defined. This kind of interference is always desired in layered systems. This would make the communication between the layers very efficient. This can be made more robust by enabling intercommunication between the modules. 10) Distinguish between virtualization and simulation. When the systems hardware is made to appear for guest operating systems or the guest applications that the OS is running on the native hardware, is called the visualization. It is the visualization of computer hardware.  On the other hand, when the guest systems is made for a different set of hardware but the actual system is running on another set of hardware, this is called simulation. In  this case, the simulating software that the OS is running, must simulate or emulate the hardware   settings that the guest systems is expecting. Simulation is always much slower than the process of visualization because the instructions are to be simulated in the software rather than the hardware, which is the case in visualization that makes visualization faster than simulation. The simulation and visualization program investigates advanced computational and experimental techniques to understand and predict physical phenomena, as well as unique image rendering methods to enhance the interpretation of complex systems and data sets. This program develops and advances simulation and visualization capabilities and applies them in a societal context. One goal is to enable scenarios for products or processes to be altered and tested in a virtual environment before any physical models are created. 11) Describe some requirements and goals to consider when designing an operating system. Requirement of designing better operating systems depends upon user and system goals. When thinking from a user perspective, we require a system that is easy to use, is reliable, safe and is also fast. Difficult and complicated operating systems would require training for the user to use it. Simple and easy interface would make the user comfortable and much more aware with the functionalities that he can use. System goals depend upon the people who are to design, create, maintain and operate the system. This would include the makers of the operating system forum. It should also keep in mind that if new updates are to be applied then they should be easy to incorporate too. So the operating system must be easy to implement design and maintain. Moreover, it should also ensure that it is flexible, reliable, efficient and error-free. 12) How does a computer system with von Neumann architecture execute an instruction? Von Neumann structural engineering is made out of three particular parts (or sub-systems): a central processing unit (CPU) memory Input/output (I/O) interfaces. The CPU is made up of 3 parts, which can be enlisted as: the control Unit (CU), one or more arithmetical logic units (ALU) and different registers. The control unit decodes the commands sent by the machine. It decides that in which direction the request is to be executed. It also controls the recovery of correct operand. TA grouping of control signs delivered by the control unit is used to handle the execution of every direction. So overall the control unit controls the data through the system issuing control signs to diverse segments. Micro operations (MO) are the control signals that are brought by every operation. All numerical and Boolean operations are performed by ALU. The registers have the capability of rapidly storing and exchanging the information and the commands that are being executed. The registers are more time efficiently accessible than the memory as they are placed on the same chip and are directly approachable by the CU. Therefore, using the registers as the wellspring of operands and as the destination of the results will make the execution much more efficient. A CPU that is placed alone on a single chip is known as a micro-processor. 13) Describe the operating systems two modes of operation. A processor in a computer running Windows has two different modes: user mode and kernel mode. The processor switches between the two modes depending on what type of code is running on the processor. Applications run in user mode, and core operating system components run in kernel mode. Many drivers run in kernel mode, but some drivers run in user mode. Two modes of   operation of an operating system is described as Kernel or   User. The hardware will be joined in the computer by a mode   bit to demonstrate the running current mode. To recognize   the user mode   or the kernel mode, there are ways on how the computer system provides   hardware backing. The operating systems kernel is used for low level    operations   in the supervision mode   that need direct access to the hardware. In order for the operating system to   interact   with different   hardware   components,   this   kind   of access is always necessary. In   supervision mode, it made very easy   for the hardware to interfere   with the hardware. All code that runs in kernel mode shares a single virtual address space. This means that a kernel-mode driver is not isolated from other drivers and the operating system itself. If a kernel-mode driver accidentally writes to the wrong virtual address, data that belongs to the operating system or another driver could be compromised. If a kernel-mode driver crashes, the entire operating system crashes. Read More