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The purpose of the priority level is for when a program is taking a long time to finish a job/command, you can change to a higher priority; or if a program is maxing your CPU you can lower the priority so other processes can run more proficiently.
Wiki User
∙ 10y ago
Wiki User
∙ 11y agoThe CPU is the "brain" of your computer or laptop. If this fails your computer may not power, give any display or cause problems when failing. It Processes everything in the computer to make things work properly
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What is priority scheduling algorithm?
The priority scheduling algorithm is a kind of CPU scheduling algorithm where the processes that wait for the CPU are scheduled according to their priority..
Where Programs are executed on the basis of a priority number?
In the Central Processing Unit (CPU).
How a Round Robin scheduling algorithm allocates the CPU to processes?
The round-robin scheduling algorithm allocates CPU time to processes by sequentially assigning the CPU to processes of equal priority that are in the state of being able to use the CPU. (Not blocked) This works by appearing to evenly distribute the CPU amongst CPU ready processes. Processes that are waiting on something, such as an I/O event, particularly waiting on the user to press Enter, are not considered for allocation. Often, there is a priority assigned to the process, which factors in the allocation strategy. Processes that are mostly I/O intensive tend to have higher priority, giving them good response time. Processes that are mostly CPU intensive tend to have lower priority, so they don't interfere with overall system responsiveness.
Advantage and disadvantage of priority scheduling?
Advantages of Priority Scheduling-1.Simplicity.2.Reasonable support for priority.3.Suitable for applications with varying time and resource requirements.Disadvantages of Priority Scheduling-1.Indefinite blocking or starvation.2.A priority scheduling can leave some low priority waiting processes indefinitely for CPU.3.If the system eventually crashes then all unfinished low priority processes gets lost.
Why DMA access to main memory is given higher priority than processor access to main memory?
In a DMA while the data is transferred between the memory and the device, if it is stopped or interrupted by any other device like CPU, it would result into a Data loss, since DMA doesnt have a program counter unlike CPU which stores it current position. In CPU if it is interrupted, it suspends it s operation without any data loss. Hence DMA has a higher priority than CPU.
How nice value is used to calculate process priority?
In Linux we can set guidelines for the CPU to follow when it is looking at all the tasks it has to do. These guidelines are called niceness or nice value.The Linux niceness scale goes from -20 to 19. The lower the number the more priority that task gets. If the niceness value is high number like 19 the task will be set to the lowest priority and the CPU will process it whenever it gets a chance. The default nice value is zero.
How computer with single CPU can run many programs?
Each running thread is allocated a time slice. When a thread's allocated time slice expires, the CPU state is saved and the next thread's state is restored. Thus each thread continues from exactly where it left off. The time slices themselves are just a few milliseconds in length. In this way many applications can appear to be running simultaneously. However, the more applications that are running, the slower they will execute because they each get fewer time slices per second. Applications are also prioritised so that high priority tasks get more CPU time than low priority tasks. Typically there are around 16 levels of priority, where 0 is the highest priority.
When an interrupt is serviced then what happens if another interrupt is raised?
It depends on the CPU architecture. Most modern CPUs support several levels of interrupts ranging from high priority to low. If the first interrupt that occurred was a high priority, then a lower priority one occurs, the high priority will continue to execute until it is done, then the the CPU will immediately jump to the lower one. Conversely, if the lower priority interrupt occurred first, it will be interrupted until the higher interrupt is serviced. For 80x86 series processors, do not confuse priority with vector. You may remember in the older days interrupt 13 belonging to the hard drive, and interrupts 3 and 4 being part of the serial port. This is not a function of the CPU but of the interrupt controller. The function of this device is beyond the scope of my answer here. 80x86 has 2 interrupt sources: maskable and non-maksable. Think of the non-maskable as the higher priority and the maskable as the lower. Most peripherals use the maskable interrupt line. Although a few, often functions of the BIOS, Fault, or Paged/Protected mode make use of the non-masked interrupt.
Write an algorithm for Round Robin CPU scheduling using?
On each system clock tick, at interval set by design...If no other runnable threads, return from clock interrupt.Save the currently running thread's context.Restore the next runnable thread's context.Return from clock tick interrupt.Note: Most modern schedulers combine round-robin with priority. In the priority scheme, any runnable thread with a higher priority than the interrupted thread takes precedence. If there are none, then round-robin applies at the current priority. If there are no runnable threads at the current priority, lower priorities are considered until we reach the idle priority thread, which, by the way, is always runnable.Also, there is usually an algorithm that adjusts thread priority dynamically. As the thread runs, if it stays runnable its priority slowly drops from its initial base priority. If it is constantly blocking and then then becoming runnable, its priority increases, often faster than it decreases. This makes interactive threads appear to be very responsive, while CPU intensive threads slowly defer to interactive threads. This is usually a good compromise between responsiveness and throughput.
What are the relationships between priority and FCFS of CPU scheduling algorithms?
this is my doubt about the non-preemptive priority scheduling. i m doing bachelor of engineering in IT and this question in end semester exam. the question is as follows:Assume you have the following jobs to be executed with one processor, with the jobs arriving in the order listed here:Process Burst Time PriorityP1 80 5P2 20 1P3 10 3P4 20 2P5 50 4Suppose the system uses priority scheduling. Draw Gantt chart and calculate average waiting time for the processes.My doubt is:suppose if we were to use non-preemptive priority scheduling, the question says the jobs arriving in the order listed, so as per the order P1 will arrive first so it will get the CPU first and in non-preemptive once a job gets CPU it will not leave CPU till the process finishes, then as per the order P2 will come and same thing repeats.... so it acts like FCFS scheduling and priority is of no use here. But my lecturer says we have to follow the priority and P2 will come first, but the line the jobs arriving in the order listed is still not letting me agree with my lecturer. Can anyone help out?
What is meant by process aging?
Process aging is the mechanism of the kernel scheduler of slowly reducing the execution priority of the process (more specifically the threads in a process) when that process or thread stays compute bound (or CPU pinned) for more than a short period of time. This mechanism allows CPU intensive processes to run at a lower priority than IO intensive (or especially interactive) processes. It is a compromise between performance and responsiveness.
How interrupts increase the performance of the CPU?
Interrupts increase the efficiency of the CPU by allowing it to stop what it's doing and go on to a different task. Interrupts are usually reserved for high priority events, for example, whenever you click a key, an interrupt is sent to the CPU that tells it to immediately stop what it is doing, save the state of the current operation it's doing, and execute the interrupt.
