Explain Dispatcher, Medium Term Scheduler In Operating System
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Dispatcher
• A dispatcher is a module, it connects the CPU to the
process selected by the short term scheduler. The main
function of the dispatcher is switching, it means switching
the CPU from one process to another process. The
another function of the dispatcher is ‘jumping to the
proper location in the user program and ready to start
execution’. The dispatcher should be fast, because it is
invoked during each and every process switch. The time
it takes for the dispatcher to stop one process and start
another running is known as the ‘dispatch latency’. The
degree of multiprogramming is depend on the dispatch
latency. If the dispatch latency is increasing, then the
degree of multiprogramming decreases.
Medium Term Scheduler
• If a process request an I/O in the middle of the execution,
then the process removed from the main memory and
loaded into waiting queue. When the I/O operation
completed, the the job moved from waiting queue to ready
queue. These two operations performed by medium term
scheduler.