University of Delhi 2010-2nd Sem M.C.A 1st yr advanced operating systems UNIVERSITY - Question Paper
Your Roll No
This question paper contains 2 printed pages.
6259
M. Sc. Computer Science / II Sem,
MCS - 202 - Advanced Operating Systems (Admissions of 2009 and onwards)
I ime 2 hours Maximum Marks 50
(Write your Roll No on the top immediately on receipt of this question paper) \ttempt all questions Parts of a question should be answered together
Q1 a Differentiate between interrupts and exceptions (2)
b. Give the disk layout of Unix file system, describing each component (5)
c What is the function of brelse algorithm7 Why is it essential to raise processor execution level m the brelse7 (3)
Q2 ix Consider the part of ttie iget algorithm given below, while (not done){
if (inode in mode cache) { if (inode locked) {
sleep (event mode becomes unlocked), continue, /* loop back to while */
What is the need for a process to start the loop from the beginning again (refer to comment above in the code), if mode is already there m the mode cache7 (3)
b Using system calls other than the read() system call, write a function that returns the size of the file whose name is passed to it as an argument (4)
c The kernel maintains an exhaustive list of free disk blocks but not of the free modes on the disk Give reasons (3)
Q3 a. What is wrong if mknodQ system call is used to create a directory7 (2)
b Consider the following program segment main(mt ac, char *av[]){ if (ac 2){
eovt H{ " <v" av|0_j < < 11 <uircctory upr,e>\ exit(l),
}
if (chdir(av[1 ]) = = -1)
cout av(l] M is not a directory'',
}
Suppose the name of the executable file for the above program is chToDir. For the following sequence of commands
/usr/Progs> chToDir OSProgs XXX>
displayed at XXX and why9 (3)
c. Explain with the help of an example, how the order of writes to the disk can minimize the corruption of file system m the event of system failure (5)
Q4 a. Explain what happens when a process wants to write data to a pipe that does not have enough space for the data to be written (4)
b. The kernel does not allow the mount to succeed if the inode reference count of the directory at which mounting is to take place is greater than one Give an example to show that if this is not followed then it may result in an error/secunty lapse (3)
c. Given the command as Is -I my File, the permissions of myFile are shown as rws xx. What is the significance of S' m the permissions? What will happen when
someone executes this file as SmyFilc0 (3)
Q5 a. Describe the three components of the context of a process (6)
b. Briefly explain \\hat is per process region table and how is it related to the region table,y (4)
|
Attachment: |
| Earning: Approval pending. |
