This document contains the answers to homework questions for the CSE-316 Operating Systems course submitted by Tej Prakash with student ID 10803816. The homework answers security issues in multiprogramming systems, circumstances for using time-sharing over a single-user system, differences between modular kernel and layered approaches in operating system design, factors for choosing a host operating system, the role of the kernel in process interaction, and advantages and disadvantages of synchronous/asynchronous communication, automatic/explicit buffering, send by copy/reference, and fixed-sized/variable-sized messages.

1. CSE-316 (OPERATING SYSTEM)
HOMEWORK 1
Submitted by-
Tej prakash
RM2801A20
10803816
Part A

2. 1. In a multiprogramming and time sharing environment, several
users share the system simultaneously. This situation can result
in various security problems.
a) What are two such problems?
Ans- a. St e a l i n g or co p y i n g on e’ s pr o g r a m s or da t a ; us i n g sy s -
te m re s o u r c e s
( CP U , m e m o r y , di s k sp a c e , pe r i p h e r a l s ) wi t h o u t pr o p e r ac -
coun t i n g ..
b) Can we ensure the same degree of security in a time shared machine as
in a dedicated machine? Explain your answer.
. Pr o b a b l y no t , si n c e an y pr o t e c t i o n sc h e m e de v i s e d by
hu m a n sc a n in e v i t a b l y be br o k e n by a hu m a n , an d th e mo r e
c o m p l e x th e sc h e m e , th e mo r e di f f i c u l t it is to fe e l
c o n f i d e n t of it s co r r e c t im p l e m e n t a t i o n .
2. Under what circumstances would a user be better off using a
time sharing system rather than a PC or single user
workstation?
Ans- When there are few other users, the task is large, and the hardware is fast, time-sharing
makes sense. The full power of the system can be brought to bear on the user’s problem. The
problem can be solved faster than on a personal computer. Another case occurs when lots of other
users need resources at the same time. A personal computer is best when the job is small enough
to be executed reasonably on it and when performance is sufficient to execute the program to the
user’s satisfaction

3. 3. In the designing of the operating system there are two
approaches modular kernel and layered approach? How are
they different?
The modularkernelapproach requiressubsystems to inter -
actwitheach otherthrough careful y
l constructedinter -
faces thatare typica l narrow (in terms of the funct
ly ion -
ali thatisexposed to externalmodules). The layered ker
ty -
nelapproach issimi r thatrespect. However, the lay
la in -
ered kernelimposes a str t
ic orderingof subsystems such
thatsubsystems at the lowerlayersare not allowed to in -
voke operationscorresponding to the upper-layersubsys -
tems. There are no such restr c i inthe modular- ernel
i t ons k
approach, whereinmodules are freeto invoke each other
withoutany constra ts.
in
Part B
4. There is guest operating system and a host operating system
like VMware? List all the factors in choosing the host operating
system?
Ans- Guest operatingsystem provides i serviceby
ts
mapping them intothe functional t provided by the host
iy
operatingsystem.a key issue thatneeds to be considered in
choosing the hostoperatingsystem iswhetheritis
suff c en l generalinterms of system cal inter
ii ty l facein
orderto be able to supportthe functional t associated
iy
withthe guestoperatingsystem.
5- The kernel is responsible for a action with the processes.
Search through the action of kernel and describe what is the
action?

4. Ans- In general, the operating system must save the state of the currently running process and re-
store the state of the process scheduled to be run next. Saving the state of a process typically in-
cludes the values of all the CPU registers in addition to memory allocation. Con- text switches
must also perform many architecture specific operations, including flushing data and instruction
caches.
6- Considering both the system level and the programmer level.
Consider the advantage and disadvantage of the following
structure.
a-)Synchronous and asynchronous communication.
A benefit of sym- metric communication is that it allows a rendezvous between the sender
and receiver. A disadvantage of a blocking send is that a rendezvous may not be required and the
message could be de- livered asynchronously; received at a point of no interest to the sender. As a
result, message-passing systems often provide both forms of synchronization
b )Automatic and explicit buffering.
Automatic buffering provides a queue with indefinite length; thus ensuring the sender will
never have to block while waiting to copy a message. There are no specifications how
automatic buffering will be provided; one scheme may reserve sufficiently large memory
where much of the memory is wasted. Explicit buffering specifies how large the buffer is. In
this situation, the sender may be blocked while waiting for available space in the queue.
However, it is less likely memory will be wasted with explicit buffering.
C ) Send by copy and send by reference
Send by copy does not allow the receiver to alter the state of the parameter; send by
reference does allow it. A benefit of send by reference is that it allows the programmer to
write a distributed version of a centralized application. Java’s RMI provides both,
however passing a parameter by reference requires declaring the parameter as a
remote object as well.

5. d ) Fixed-sized and variable-sized messages.
The implications of this are mostly related to buffering issues; with fixed-size mes- sages, a
buffer with a specific size can hold a known number of messages. The number of variable-
sized messages that can be held by such a buffer is unknown. Consider how Windows 2000
handles this situation: with fixed-sized messages (anything< 256 bytes), the messages are
copied from the address space of the sender to the address space of the receiving process.
Larger mes- sages (i.e. variable-sized messages) use shared memory to pass the message