Question

True or false

1) OS uses multiple queues in process scheduling. At any time instance, the PCB of a process can only belong to one queue.

2)OS uses the \proc pseudo-file system to store the statistical information of a process. Even if a process is terminated, we can still find the statistical information on of this process from the \proc pseudo-file system.

3) When a process successfully calls an exec*() function to run a program, the executed program will inherit the PID of the calling process.

4) Since asynchronous I/O will not block the calling process, the processes that calls asynchronous I/O will never transit from the running state to the wait state during asynchronous I/O.

Answer 1

1) OS can have multiple queues for scheduling examples: multi level queue, multi level feedback queue scheduling.

A process can be moved from one queue to another by moving its PCB but, it can be in one PCB at a time. Hence the statement is TRUE

2) In a linux OS, you can go to /proc/<pid>/ directory to find information about the process(also information recorded since it started executing). Linux calls its processes and threads as task, so its appropriate to say /proc/<task-id>/ directory. Hence TRUE

3) A child process once created can call execute() to replace its address space with a new process's address space. But it won't inherit its parent's process id. Hence FALSE

4) If a process has started an asynchronous I/O(and later it will invoke the completion handler), it can also start a synchronous IO(to implement this we will have to invoke the completion handler for async IO after completion of synchronous I/O), now the process can enter into blocked state. Hence FALSE

Edit: In case of asynchronous IO, lets say an async IO operation is initiated and the process continues with operations not dependent on the data that will be generated by the async IO operation. After all the non dependent operations have been finished and the IO operation is still not finished, the process can still go to a wait state(as now it has to wait anyways for the IO operation to finish),