Preamptive & priority based scheduling......

[sacrpio]

priority based preemptive scheduling

Any body can tell me please, IS THERE ANY DIFFERENCE BETWEEN PREAMPTIVE & PRIORITY BASED SCHEDULING.

tHANKS

 

[lunark]

priority based scheduling

preamptiv is base on the priority based scheduler.

preamptiv means if there have th hight priority task want to run, the low priority task will push to stack. and the prious task run at once.

As it to the pc os, most of them just have two priority, system and user.

But he rtos alwayls have many task have different priority. and the run time of every task can be defined because of the preamptiv.

So it is a RTOS real time os

 

[banh]

preemptive rtos

Any body can tell me please, IS THERE ANY DIFFERENCE BETWEEN PREAMPTIVE & PRIORITY BASED SCHEDULING.

tHANKS

preemptive means the OS can interrupt a running task to possbily run another task before resuming back to the previous task...

priority scheduling means each task has its own priority..these priority can be assigned (fixed) at the beginning, or can be dynamically re-assigned while all the task are running.

several priority-based, and preemptive scheduling algorithms: Rate Monotinic Scheduling (RMS) - the shorter period of task, the higher its priority, Deadline Monotonic Scheduling (DMS) - the shorter deadline of a task, the higher its priority,

Dynamic priority scheduly: ICPP (Immediate Ceiling Priority Protocol)...

Those are stuff from books...

 

[devennan]

preemptive priority based scheduling

Any body can tell me please, IS THERE ANY DIFFERENCE BETWEEN PREAMPTIVE & PRIORITY BASED SCHEDULING.

tHANKS

the most important difference is that in preamptive Priority based scheduling the kernel can pre empt the process or Task ( puts it in a Q of watingtask) if a high priority task arives for execution but in Priority based scheduling at run time say

A task is running and a higher priority task comes it will have to wait till the running task completes it share of time (it is not necessary that the task has to be completed ) after this task is over can the high priority task get CPU resources

Added after 10 minutes:

Any body can tell me please, IS THERE ANY DIFFERENCE BETWEEN PREAMPTIVE & PRIORITY BASED SCHEDULING.

tHANKS

the most important difference is that in preamptive Priority based scheduling the kernel can pre empt the process or Task ( puts it in a Q of watingtask) if a high priority task arives for execution but in Priority based scheduling at run time say

A task is running and a higher priority task comes it will have to wait till the running task completes it share of time (it is not necessary that the task has to be completed ) after this task is over can the high priority task get CPU resources

 

[vini_natv]

preemptive priority-based scheduling

The rate monotonic scheduling (RMS ) and Earliest Deadline scheduling algorithms will explain the concepts in detail

 

[ariyan]

preemptive rtos

Actually priority scheduling is nothing but preemptive.
With a preemptive priority-based scheduler, each task has a priority and the kernel
ensures that the CPU is allocated to the highest priority task that is ready to run.
This scheduling method is preemptive in that if a task that has higher priority than
the current task becomes ready to run, the kernel immediately saves the current
task’s context and switches to the context of the higher priority task.

 

[atcm]

dynamic priority based scheduling in rtos

There are two type of RTOS, which is the preemptive and non-preemtive. The preemptive RTOS can further divided into round-robin and priority based.

For the round-robin preemptive RTOS, every task executes equally for fix amount of time. When an interrupt happen, the schedular will allow the ISR to preempt the current task. When the ISR finish the latest task that is preempted will continue to run.

For the priority based preemptive RTOS, task with higher priority get more change to execute tahn task with lower priority. When an interrupt happen, the schedular will allow the ISR to preempt the current task. When the ISR finish task with the highest priority will continue to run.

For a preemptive RTOS, the schedular automate the task switching.

Non-preemptive RTOS is also known as co-operative RTOS. Task switching is done by all the tasks. So the programmer has to determine which task will run after the current task. For task switching, the current task has to activate the next task before stopping itself.