Schedulers in OS

 Q.   1- Activation of interactive program

        2-  interrupts and I/O completions

        3- Most operational OS calls

whenever one of the above event occurs OS invokes which one of the scheduler


a  long term scheduler

b mid term scheduler

c  short term scheduler

d  none of these

also explain why ?

Vivek Vikram Singh @vivek14
5 Jun 2016 11:10 pm

Please write PROPER title of the question using exam name or topic name with some keywords from question. This kind of title are considered bad, they doesn't say anything about topic/subject of question, therefore getting less/ no attention by students or mentors here.

Arvind Rawat @arvind.rawat
6 Jun 2016 02:52 pm

The short-term scheduler (also known as the CPU scheduler) decides which of the ready, in-memory processes are to be executed (allocated a CPU) next following a clock interrupt, an IO interrupt, an operating system call or another form of signal. In practice, the short-term scheduler is invoked whenever an event (internal or external) causes the global state of the system to change. Given that any such change could result in making the runninng process suspended or in making one or more suspended processes ready, the short-term scheduler should be run to determine whether such significant changes have indeed occured and, if so, to select the next process to be run. All of the above mentioned events can cause rescheduling by virtue of their ability to change the global system state, hence OS invokes short-term scheduler in these cases.