As discussed in Section 1.3, there are many scheduling algorithms, each with its own parameters. As a result, selecting an algorithm can be difficult. The first problem is defining the criteria to be used in selecting an algorithm. The criteria are often defined in terms of CPU utilization, waiting time, response time, or throughput. To select an algorithm, we must first define the relative importance of these elements. Our criteria may include several measures, such as these:
• Maximizing CPU utilization under the constraint that the maximum response time is 1 second
• Maximizing throughput such that turnaround time is (on average) linearly proportional to total execution time
Once the selection criteria have been defined, evaluate the algorithms under consideration. There are various methods available to evaluate the algorithms: Deterministic Modelling, Queuing Models, Simulation, and Implementation. Among these methods, simulation is used to evaluate the algorithm.
To get a more accurate evaluation of scheduling algorithms, we can use simulations. Running simulations involve programming a model of the computer system. Software data structures represent the major components of the system. The simulator has a variable representing a clock. As this variable’s value is increased, the simulator modifies the system state to reflect the activities of the devices, the processes, and the scheduler. As the simulation executes, statistics that indicate algorithm performance are gathered and printed.
The data to drive the simulation can be generated in several ways. The most common method uses a random-number generator that is programmed to generate processes; CPU burst times, arrivals, departures, and so on, according to probability distr...
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...heduling multiple processes on different processors is one of the most challenging problems in multi process operating system. Real time short term scheduler is well adapted to multiprocessor scheduling problems.
In this project, a short term scheduler is introduced for scheduling the tasks in multi process real time systems. The scheduler based on moving the events on a logical time scale and it simultaneously allocates different processes to different processors on the system.
The analysis of output obtained from the scheduler reveals that minimization of waiting time and maximization of CPU utilization is accomplished. It also states that average waiting time is waived before any process is being serviced. The overall computed summary statistics reveal that Real Time Short Term scheduler can be the solution for scheduling the processes in a multiprocessor system.
The tuning strategy process parameters are designed such that they do not effect 1) the maximum throughput of multi-core processors and 2) the overall execution time of workloads. There have been experiments
Windows hardware’s has played a vital role in current technology of computer era. Computer application has significantly changed the workloads and manual records and information keeping has been significantly managed easily. This has been tremendously associated with the respective improvements with the software and hardware application development and Windows Xp and windows 7 have been most powerful operating system used by many computer applicants and users.
Based on implementation of FMULT_ACCUM and control unit, this system was implemented in three different types. Bit serial, pipeline and single resource. This paper discusses the design and implementation of bit serial architecture. The main motive behind bit serial implementation was to reduce the area and cost at the expense of speed.
Having block scheduling is one of the main concerns of the Aldine Independent School District. Block scheduling is when students have half of their classes one day and the other half the next. There has been some complaints about how block scheduling decreases students’ focus, but there has also been many compliments about how it improves students’ education. Michael D. Rettig, President of School Scheduling Associates, states that more schools are considering block scheduling and more than thirty percent of schools in the country already have it [bandwagon]. The Aldine Independent School District has made the reasons remarkably clear as to why they have switched to block scheduling and they are: better test scores, better grades, and improvement of teacher-student interaction.
Concurrency is an essential part of multitasking; after all using concurrency signifies executing several tasks at the same time or at least to give that impression, “Concurrency is an illusion of parallelism. Thus, two tasks are concurrent if there is an illusion that they are being performed in parallel, whereas, in reality, only one of them may be performed at any time. ” (D.M.Dhamdere, 2006, p91).However, in the case of multi-core processors or multi-processors true parallelism can be achieved. In any case, in order to maintain the illusion of parallelism, executing alternately various tasks is essential, therefore, determining which task execute next is particularly serious. That is where scheduling comes forth since according to D.M.Dhamdere(2006,p91) scheduling is selecting the next process to be serviced, in order to do so different policies can be used, depending on the context in which the program is going to be used, of course combinations are also possible. Let’s focus mainly on pre-emptive scheduling commonly (used by threads) and cooperative scheduling (used by agents). Firstly pre-emptive scheduling, in this configuration, a process, thread or application can be pre-empted. This means that it can be suspended by ...
As is suggestive of its name, an operating system (OS) is a collection of programs that operate the personal computer (PC). Its primary purpose is to support programs that actually do the work one is interested in, and to allow competing programs to share the resources of the computer. However, the OS also controls the inner workings of the computer, acting as a traffic manager which controls the flow of data through the system and initiates the starting and stopping processes, and as a means through which software can access the hardware and system software. In addition, it provides routines for device control, provides for the management, scheduling and interaction of tasks, and maintains system integrity. It also provides a facility called the user interface which issues commands to the system software. Utilities are provided for managing files and documents created by users, development of programs and software, communicating between users with other computer systems and managing user requirements for programs, storage space and priority. There are a number of different types of operating systems with varying degrees of complexity. A system such as DOS can be relatively simple and minimalistic, while others, like UNIX, can be somewhat more complicated. Some systems run only a single process at a time (DOS), while other systems run multiple processes at once (UNIX). In reality, it is not possible for a single processor to run multiple processes simultaneously. The processor of the computer runs one process for a short period of time, then is switched to the next process and so on. As the processor executes millions of instructions per second, this gives the appearance of many processes r...
...ion in real-time is possible, since applications with the back office ERP System are integrated. So, the time integration is a trivial issue. Some authors confirm that if support processes apply this form of integration, it would not have negative impacts on any of the critical factors in the industry [13].
The Central Processing Unit (CPU) is the brains of the computer where most of the calculations take place and it is the most important element of a computer system. For the PC the CPU is housed in a chip (known as the microprocessor) such as the Inte...
The TMA system relies on eight processes which include the following: 1) the communications manager which shares information between its databases, 2) the radar daemon which has a link between the TMA and the controllers computer, 3) the weather daemon which uses weather information from the national weather service, 4) the timeline graphical user interface which receives and uses information from the traffic management controllers computer, 5) the route analyzer which decides which route the aircraft will use, 6) the planview graphical user interface which uses input from the controllers and displays the information, 7) the trajectory synthesizer which determines the estimated time of arrival and the descent profile of the aircraft, and 8) the dynamic planner which determines the runway and the sequences of the other incoming traffic.
The next step is to choose the criteria that we are going to take into consideration. In my opinion, the most important criteria are the following (their order does not indicate their importance):
In this course, we developed an operating system quite close to a real world operating system but it included limited features. It was developed in C language and incorporated features such as its own boot loader, we developed system calls using software interrupt, a file system that allowed us to create, read and delete a file. The interface was basically command line and was capable of executing some limited commands like dir, copy, delete, type, execute and kill process. It also supports multitasking using timer interrupts and scheduler implemented in round robin fashion. The things that were missing or implemented partially in our system were full-fledged graphical interface, memory management and FAT file system. These features are necessary to call our system as a real world operating system.
When an executable file is loaded into memory, it is called a process. A process is an instance of a program in executing. It contains its current activity, such as its program code and also the contents of the processor’s register. It generally includes the process stack, which contain temporary data, and a data section, which global variables. During runtime, it may include a heap, or dynamically allocated memory. In contrast with a program, a process is “an active entity, with a program counter specifying the next instruction to execute and a set of associated resources” (Operating System Concept 106). A process is a program that executes a single instance of a thread. Multiple threads can exist which allows more than one task to perform at a time. Multithreaded processes may share resources such as code, data, and file section. They do not share resources such as registers and stack.
Production scheduling: create appropriate schedules for all the level on the organization, maximize of efficiency of
Many industrial plants require a central computing facility to collect data from various sensors and then to act accordingly. For example, in a chemical engineering plant, as the pressure in one vat increases the computer registers this, and opens a release valve slightly while also adjusting the boiler temperature.
-Packet scheduler check the order of packet transmission to achieve the Quality of Service for multimedia streaming.