The scheduler's job is deciding when each process gets a shot at CPU time and for how long. While their approaches are different, they all follow roughly the same strategy:
First, assume that the CPU can run only one process at a time. CPUs with multiple cores are treated as multiple CPUs that can only run a single process or thread. Therefore the scheduler will determine that X amount of processes can be in a "running" state, where X is the number of cores or CPUs.
Second, assume that any process waiting for I/O is not going to accomplish anything while on the CPU, so do not schedule the process until its associated I/O operation has been COMPLETED by the hardware in question.
Third, assume that not all processes are equal in importance. Some processes really do not need much CPU time, so do they really need to preempt a process that does need plenty of CPU?
Fourth (In preemptive scheduling.), the kernel and not the processes, have full control over when context switching occurs, including when a process's time slice expires. Further, a process can and should be able to preempt itself when asking for I/O so that the kernel can arrange the operation with the drivers.
Finally, assume that all processes are flawed and just waiting to try and take each other's stuff. The scheduler itself will not implement memory protection, but it does need to know how to interpret whatever memory management is in place for context switching purposes.
All are functions of the OS.
No. The Job Scheduler is the high-level scheduler.
What is job scheduler and dispatcher?
1. Job scheduler is also called long term scheduler and CPU scheduler is called short term scheduler. 2. Job scheduler selects the processes from the job pool and load them in to the memory for execution. in other hand CPU scheduler selects among the processes that are in ready to execute and allocate the CPU to one of them. 3. CPU scheduler is faster than the process scheduler.
Long Term Scheduler
function of memory management
I don't think cells need an OS to function properly
long-term scheduler...
ULE scheduler was created on 2003-01-26.
1. Job scheduler is also called long term scheduler and CPU scheduler is called short term scheduler.2. Job scheduler selects the processes from the job pool and load them in to the memory for execution. in other hand CPU scheduler selects among the processes that are in ready to execute and allocate the CPU to one of them.3. CPU scheduler is faster than the process scheduler.Read more: What_is_the_difference_between_the_job_scheduler_the_CPU_scheduler
Long-Term SchedulingLong-term scheduling performs a gatekeeping function. It decides whether there's enough memory, or room, to allow new programs or jobs into the system. It limits the degree of multi-tasking to prevent slow performance on currently-running programs. When a job gets past the long-term scheduler, it's sent on to the medium-term scheduler. Medium-Term SchedulingThe medium-term scheduler makes the decision to send a job on or to sideline it until a more important process is finished. Later, when the computer is less busy or has less important jobs, the medium-term scheduler allows the suspended job to pass. Short-Term SchedulingThe short-term scheduler takes jobs from the "ready" line and gives them the green light to run. It decides which of them can have resources and for how long. The short-term scheduler runs the highest-priority jobs first and must make on-the-spot decisions. For example, when a running process is interrupted and may be changed, the short-term scheduler must recalibrate and give the highest-priority job the green light.
ฟังก์ชันล่าสุดSymbian OS