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Advanced Operating System
1. Irfan Ahmad:
Q1: How does curios system makes an operating system even more reliable?
Q2: How can we differentiate between traditional micro kernal operating system service and curios
service?
Q3: Discuss any micro kernal operating system that are closely related .
Q4:what does we mean by saying light weight distribution in surious representation.
Q5:Discuss the limitations and points of criticism in curious system.
Q6:Discuss the following features regarding curious time management networking scheduling .
2. Zahida Shareef:
Q1. Differentiate static and dynamic algorithms?
Qno2. How uni processor systems work without blocking?
Qno3.How transient overloads occur in hard real time systems?
Qno4.Describe priority inversion?
Qno5.what is priority inheritance?
Qno6. What are the ceiling protocols?
3. Sabir Kamran:
1)
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3)
4)
5)
What is Robotic Operating System (ROS)?
What are nodes in ROS?
How we debug a single node?
For what Purpose , We use Visualization and Monitoring in ROS?
What is dynamic transformation tree?
6) What is Collaborative Development in ROS?
Peer-to-Peer is a system in ROS, what do you know about it? Describe it.
4. Majid Khan
1) In time driven scheduling model, the auther use _____________________to evaluate the
currently used real time algorithms. Simulator.
2) A pair of new experimental algorithms used by the author of “Time driven scheduling model for
RTS” called__________________________.
BEValue1 & BEValue 2
3) In time driven scheduling model ,using simulator at 246% overloaded situation , the deadline
scheduler have ____________function values.
Low
4) In time driven scheduling model , Surprisingly, STP algorithm gives___________________results
in in both 123% and 246% Overloaded conditions.
Better.
5) In time driven scheduling model ,the simulations reveals that ________________________
Scheduling algorithms is best choice in underloaded condtions.
SlackTime
6) In time driven scheduling model, _____________________is used to describe the performance
of the existing Real time Scheduling algorithms.
Time Value function
5. Amir Hasnain
Q1.what is NOX operating system for networks,explain with examples.
Q2.explain the components of a NOX-based network.
Q3. write note on programmatic interface of NOX network.
Q4. Write short note on HOME NETWORKING.
Q5. discuss about User based VLAN tagging in NOX networks.
6. Farrukh Jibran
Q1. What is transient overload?
For hard real time systems, it is necessary for all critical processes to be scheduled using worst
case estimates. However, it will usually be the case that some process deadlines are soft, in the
sense that the occasional deadline can be missed, then system is said to be experiencing a
transient over load.
Q2. What is rate monotonic Algorithm?
In Rate monotonic algorithm processes are given priority on the basis of their period.
Shorter the period higher will be the priority.
Q3. Differentiate between Periodic and Aperiodic processes?
The periodic processes will repeat themselves after the specified time. While aperiodic process
will occur occasionally. Periodic processes will have time period.
Q4. What are the characteristics of periodic processes?
 Their Period
 Their Deadline
 Their required execution time (per period)
Q5. Differentiate between Static and Dynamic Algorithms?
 A static approach calculates (or pre-sets) schedules for each process in advance.
 Dynamic Algorithms calculates the schedule as the process start execution.
 Static or offline scheduler, all scheduling decisions (tables) are made before the running of
the system.
Q6. What is period transformation technique?
To make Rate Monotonic algorithm applicable to Transient overloads. We transform the period
of processes. e.g.
Let P1 and P2 with period 12 and 30 and average execution times of 8 and 3 units respectively
P1 will have higher priority. P1 will meet its deadlines but P2 will miss it. Transform P2 , such
that we have new process P2` which has cycle of 10 units and 1 unit of execution time(on
average)in each period. P2` have shorter period so higher priority. Now P2 will meet the
deadline.
7. Fayyaz Hussain
Q.No.1:What is the critical theme of “Energy Efficient Voltage Scheduling for RealTimeOperating Systems”?
Ans:This paper applies the concept of real-time process scheduling to a Dynamic Voltage
Scaling (DVS) microprocessor.
DVS allows a microprocessor to save energy by operating at the optimal voltage for the
task at hand.
Q.No.2: Discuss three ways through which energy consumed by a microprocessor is
reduced?
Ans: There are following three methods through which energy consumed by a microprocessor is
reduced:
 Reduce the number of operations performed,
 Reduce the switched capacitance of each operation,
 Reduce the operating voltage.
Q.No.3: Explain the relation between Maximum clock speed of microprocessor and energy
consumed by microprocessor through an equation?
Ans: Relation between Maximum clock speed of microprocessor and energy consumed by
Microprocessor is given below:
Here fmaxis Maximum clock speed of microprocessor and Eop is energy consumed by
microprocessor on each operation. And c is constant.
There is another equation which explain Maximum clock speed of microprocessor and operating
voltage.
we can decrease the energy consumed
1. by slowing the processor clock
2. reducing the operating voltage
Q.No.4: Define Dynamic Voltage Scaling (DVS)?
Ans: DVSis a technique that allows a voltage scheduler routine
 to alter a microprocessor’s operating voltage at run-time.
 The voltage scheduler analyses the state of the system and determines the optimal target
voltage.
 To use task deadlines, and to determine the length of task.
Q.No.5: Define an optical voltage scheduling?
Ans:An optimal voltage schedule to be one for which
 all tasks complete on or before deadline.
 The total energy consumed is minimized.
Q.No.6: Discuss the complexity of Algorithm “Energy Efficient Voltage Scheduling for
Real-Time Operating Systems” ?
Ans:
The complexity of Algorithm “Energy Efficient Voltage Scheduling for Real-Time Operating
Systems” is given below:
• ntasks to schedule
• O(n) speed settings to consider for each task
• O(n) linked tasks requiring adjustment for each setting
• Total complexity: O(n3)
8. Abdul Sammi:
Q1. What is spring kernal?
Q2. What is the importance of kernal in OS?
Q3. Explain the interrupt in OS.
Q4. How hard real time OS is critical?
Q5. What is the difference between soft R.T.O.S and hard R.T.O.S ?
Q6. Explain the main functions of kernel
9. Kamran
Q1. What is the goal of GRACE-OS?
Ans. The major goal of GRACE-OS is to support application quality of service and save energy. To achieve this goal,
GRACE-OS integrates dynamic voltage scaling into soft real-time scheduling and decides how fast to execute applications
in addition to when and how long to execute them.
Q2. What are the results of GRACE-OS after experiment?
Ans. (1) The demand distribution of the studied codec is stable or changes smoothly. This stability implies that it is
feasible to perform stochastic scheduling and voltage scaling with low overhead; (2) GRACE-OS de-livers soft
performance guarantees by bounding the dead-line miss ratio under application-specific requirements; and (3) GRACE-OS
reduces CPU idle time and spends more busy time in lower-power speeds
Q3.Explain DVS mechanism.
Ans. Dynamic voltage scaling (DVS) is a common mechanism to save CPU energy. It exploits an important characteristic
of CMOS-based processors: the maximum frequency scales almost linearly to the voltage, and the energy consumed per
cycle is proportional to the square of the voltage. A lower frequency hence enables a lower voltage and yields a quadratic
energy reduction. The major goal of DVS is to reduce energy by as much as possible without degrading application
performance. The effectiveness of DVS techniques is, therefore, dependent on the ability to predict application CPU
demands over estimating they can waste CPU and energy resources, while underestimating them can degrade application
performance.
Q4.Write summary of the GRACE-OS.
Ans. Overall, our experimental results show that GRACE-OS provides significant benefits for QoS provisioning and
energy saving and incurs acceptable overhead. GRACE-OS meets almost all deadlines in a lightly loaded environment
(with-out CPU competition) and bounds deadline miss ratio under application statistical requirements in a heavily loaded
environment. Compared to other systems with deterministic scheduling and DVS, GRACE-OS spends more CPU time in
lower-power speeds, thus saving energy. When executing a single high-demand application, stochastic DVS primarily
contributes to energy saving, reducing normalized energy by 10%-72%. When executing multiple applications
concurrently, stochastic scheduling and DVS both contribute to energy saving, reducing normalized energy by 7%64%.We also find that GRACE-OS’s efficiency is limited by the discrete speed options, especially when executing a
single low-demand application and when changing the statistical performance requirement from 0.95 to 0.99. This is
similar to Pillai and Shin’s finding, which shows through simulations that the speed availability profoundly affects energy
saving of real-time DVS algorithms
Q5.Explain Stochastic SRT Scheduling.
Ans. Multimedia tasks present demanding computational requirements that must be met in soft real time (e.g., decoding a
frame within a period). To support such timing requirements, the operating system needs to provide soft real-time
scheduling, typically in two steps: predictable cycle allocation and enforcement. The key problem in the first step is
deciding the amount of cycles allocated to each task. GRACE-OS takes a stochastic approach to addressing this problem:
it decides cycle al-location based on the statistical performance requirement and demand distribution of each task. The
purpose of this stochastic allocation is to improve CPU and energy utilization, while delivering statistical performance
guarantees.
Q6. Define limitation of energy saving due to few speed options in the HP Pavilion laptop.
Ans. GRACE-OS will result in more benefits, if there are more speeds available and frequent speed changes incur low
overhead. In general, such expectation can be examined in three ways: (1) using a trace-based simulator to experiment
with an ideal processor that supports continuous DVS, (2) converting an optimal speed to two available speeds and (3)
applying GRACE-OS to processors that support continuous DVS (e.g., lp ARM.
10. Rubina
Q1:What is the result of the trand of embedded system and convergence of application?
Ans: As a result of these trends, there is a growing consensus that the only design reuse
techniques can close the fast growing gap between the potentials of semiconductor production
technologies and traditional design productivity
Q2:Explain the system level synthesis flow by algorithm to architecture methodology
Ans: Traditionally, application-specific systems have been implemented using the algorithm-toarchitecture methodology.Figure 1 illustrates the new system-level synthesis flow. RTOS
provides isolation and interface to application and algorithm developers and compilation tools
from one side and to architecture and integrate circuits designs from the other
Q3:Define system on silicon? Why it demand more carefull design?
Systems-on-silicon demand more careful design because design revisions are both costly and
time-consuming. They also require very high-quality software for several reasons: the software
will definitely be hard to observe and therefore debug due to pin limitations; the software may
be hard to change after fabrication; and the hardware cannot be easily changed to
accommodate software performance problems.
Q4:What are the state of RTOS(real time operating system) and contetxt switch?
The RTOS considers a process to be in one of three states: waiting, ready, and executing. In a
uniprocessor system, only one process can be executing at any time. Some processes may be
waiting for data or other events. Processes which are not blocked for external events but are
not currently executing are considered ready. The transfer of execution from one process to
another is called a context switch. To execute a context switch, the RTOS must save the state of
the old process, determine what process will next obtain the CPU, and then set the CPU state to
that process’s state.
Q5:Write the scheduling policies given by Stankovic et al ?
Stankovic et al. provide following good survey of real-time scheduling techniques



A cooperative scheduler relies on the current process to give up the CPU before it can
start the execution of another process. Cooperative multitasking is suitable for
extremely simple systems, such as digital filters with purely periodic inputs, but is not
used in sophisticated embedded systems.
A static priority-driven scheduler can preempt the current process to start a new
process. The highest-priority ready process is always the currently executing process.
Priorities are set before the system begins execution.
A dynamic priority-driven scheduler can redefine the process priorities at run time. The
highest-priority ready process is still the currently-executing process, but since the RTOS
can redefine priorities, the scheduling policy is embodied in the dynamic choice of
priorities.
Q6:What is mean by temporal constrints on the process behavior ?
Processes and tasks generally have some sort of temporal constraints on their behavior. The
exact nature of these constraints depends on the scheduling model, but several types of
temporal measurements of process/task performance are used.forexample A deadline is the
time at which a process must finish execution after being initiated. The period of a periodic
process or task is the interval between initiating successive executions
11. Mudassir
Q:1: What are the advantages and functions of Caernarvon secure embedded operating system?
Ans: The Caernarvon operating system was developed to demonstrate that a high assurance system for smart card was
technically feasible and commercially viable. This approach facilitated implementation of a formally specified, mandatory
security policy providing multi level security, suitable for government users.
Caernarvon OS include a strong cryptographic library that has been separately certified under the common criteria at EAL5+ for
use with other systems.
Q No:2 What were the goals of the Caernarvon secure embedded operating system project?
The Caernarvon project objectives included the following key items:
=>To use the preferred- hardware based approach for high assurance.
=>To guarantee isolation of data belonging to different organizations and also facilitate controlled sharing of data.
=>To provide built in cryptographic functions.
=>To provide privacy preserving two way authentication protocol.
=>To devise a secure method for downloading untrusted code.
=>To successfully complete a common criteria evaluation.
Q No:3 What were the platform-specific constraints, which were to be obeyed by the Caernarvon secure embedded system
project?
To comply with the ISO 7816 standard.
To comply with smart card power limitations.
To have sufficient transaction speed for our anticipated applications.
Q No:4 How authentication is performed in Caernarvon operating system?
Caernarvon authentication is application independent and is enforced by the system kernel. It incorporates following
mechanism.
A device verifies the existence of a certified secret key on the other party.
The device negotiates or exchange information to establish:
(i) a common session key for subsequent operations
(ii) Common access class for subsequent classes.
Q No:5 Describe the influence of the Caernarvon project?
Through the Caernarvon project IBM research has had significant external impact in the areas of cryptography, mandatory
security policy and authentication. The Caernarvon cryptographic library implementation has completed the common criteria
evaluation process and has earned EAL5+ certification.