I saw this question somewhere
Four processes p1, p2, p3, p4 – each have sizes 1GB, 1.2GB, 2GB, 1GB. And each processes is executed as a time sharing fashion. Will they be executed on an operating system.
I think the answer should be No,they are not executed on operating system because OS is itself a process and it will be running in parallel to these processes.There will be switching between processes from time to time with the help of dispatcher.
but i am getting the doubt that answer can also be yes because it uses every process uses memory which is managed by theb operating system .
please help me figure out the right answer for the question..
This depends entirely on the OS in question.
As well as starting processes (and possibly consisting of processes), an operating system generally provides services to the processes that run on it, such as memory management, file systems, communications and so on.
In that context, these processes can be said to be running on top of the OS. In other words, processes generally are of little use unless they communicate outside of themselves.
In any event, the dispatcher (or scheduler) tends to be an integral part of the OS so having your processes scheduled means that you’re running on top of that OS.
Modern operating systems also provide paging of memory as well which means that you can use a lot more virtual memory than there is physical memory – the OS is then responsible for handling requests for memory that has been paged out.