Real-Time Audit and Defense Course

• Real-Time Audit and Defense course presented by Dr. Ahmed Elngar, Associate Professor and Head of Computer Science Department at Beni-Suef University and Faculty of Computers and Information Technology, American University in Emirates.

Course Syllabus (UCCE 3223)

• Course covers Real-Time Auditing and Defense
• Has a total of 3 hours
• Includes 2 hours of practical, hands-on training
• 2 hours are dedicated to theoretical aspects.
• The prerequisite for this course is UCCS 3107.
• The course defines applications, and compares hard vs soft real-time systems.
• Covers reference models of real-time systems and commonly used approaches to hard real-time scheduling.
• Touches on clock-driven scheduling and priority-driven scheduling, as well as scheduling periodic and sporadic tasks
• Discusses multiprocessor scheduling, resource access control, flexible computations, and tasks with temporal distance constraints.
• Includes real-time communication, real-time operating systems, and real-time programming.

Text Book

• The course utilizes "R. Mall, Real-Time Systems" as a textbook, published by Pearson in 2008
• It is supplemented with handouts.

Course Plan

• Introduction
• Task Scheduling : Uniprocessors, Multiprocessors
• Commercial Real-Time Operating Systems
• Real-time communications
• Real-time databases

Reference Books

• Jane Liu, Real-Time Systems, Pearson, 2000
• C. Krishna and K. Shin, Real-Time Systems, McGraw-Hill, 2000

Real-Time Systems

• Real-time System: Requires time to be quantitatively expressed to describe behavior.
• Performance is described by listing inputs and corresponding system responses.

Important Characteristics of Embedded Systems

• Embedded systems respond to events with external input, data processing, and external output.
• Automobile airbag systems are examples.
• Airbags deploying within 10ms of collision detection illustrates system timing requirements

Embedded Systems

• Embedded Systems = Hardware + RTOS + Application Program

Real-Time OS

• Real-Time OSs differ from Traditional OSs and are time bound.
• Embedded systems respond to external inputs
• If the response is late, the system fails.
• General purpose OSs are not designed for real-time use, but Real-time OSs help tasks meet deadlines

Characteristics of Embedded Systems

• Real-time systems have tasks associated with time constraints, e.g., deadlines.
• It follows the correctness criterion, the results should be logically correct within the stipulated time.

Considerations

• Safety and Task Criticality: Critical tasks are those where failure causes system failure, necessitating obstacle avoidance
• A safe system does not cause damage.
• A safety-critical real-time system is one where failure causes severe damage

More Characterisitics

• Concurrency requires the system to respond to independent events via separate tasks
• The same inputs can lead to different outcomes (Non-determinism)
• Systems are distributed with feedback structures and often implemented on custom hardware

Characteristics Continued

• Embedded Systems are reactive, with ongoing computer-environment interaction
• They demonstrate stability, important tasks will perform acceptably under overload.
• They perform exception Handling.

Safety and Reliability

• Safe System: Does not cause damage even when it fails.
• Reliable System: Operates for a long time without any failure.
• These are independent concepts in traditional systems.
• In traditional systems, safety and reliability are separate concerns.
• A system can be safe but unreliable and vice versa.

Safety Critical System

• Interrelated in safety-critical system
• Failure would result in severe damage
• Safety can be ensured only through increased reliability.

Fail-safe state

• An unreliable system can be made safe upon a failure by reverting to a fail-safe state.
• A fail-safe state means no damages can result if a system fails in this state
• Traffic lights blinking orange in all directions.

Fail-Safe Word Processing Program

• The document being processed has been saved onto the disk
• Fail-safe states help separate the issues of safety and reliability.
• Systems can always be made to fail in a fail-safe state.

Safety-Critical Sytems & Navigation

• For a safety-critical system no fail-safe state exists
• For a safety-critical system on an aircraft, shutting down the engine when the navigation system fails, wont help

Highly Reliable System Design

• Error Avoidance
• Error Detection and Removing
• Fault Tolerance

Fault Tolerance in Real Time Systems

• Essential Idea: Provide Redundancy
• Hardware fault-tolerance masks the effects of a hardware fault
• Software fault-tolerance masks the effects of a program fault

Fault Tolerance Methods

• Hardware FT: Built in self test (BIST) and Triple modular redundancy
• Software FT: N-Version programming and Recovery Blocks

Triple Modular Redundancy

• C1, C2, and C3 are redundant copies of a component that are voted on to select the majority result.

N-version programming

• Software fault tolerance technique, inspired by TMR of hardware.
• Different teams develop the same software.
• It has unsatisfactory performance because faults are correlated in the different versions and all version fail for similar reasons.

Recovery Blocks

• Software Fault Tolerance using recovery blocks
• It tests blocks after completing
• Runs alternatives if the initial test fails.

Modern Embedded Systems

• They incorporate Application-Specific hardware and programmable processors and mechanical transducers and actuators for performance and low power.

Embedded Systems: Block Diagram

• Contains control panel, controller processes, ASIC, processor, real-time OS, UI processes, and dual-ported RAM with CODEC.

OS in Embedded Device

• It supports multitasking, scheduling, synchronization, timing aspects, and memory management
• Supports file systems, networking, graphics displays, interfacing, scheduling, buffering, security, and power management.

Why an OS

• A recent cell phone system contained over five million lines of code
• Typical Embedded OS license fees are low
• Some simple low-end devices might not need an OS, but new devices are getting more complex.

Current Usage

• What Types of Processors are used?
• What Operating Systems are used?
• What Programming Languages are used?
• 2006 Market Survey of design engineers: Embedded Systems Design Magazine.

Processors

• 32-bit processors are dominantly used in new embedded designs in 2006 embedded market survey.
• Processor Architectures Widely Used: ARM, X86, PowerPC, MIPS, Xscale (ARM), and Renesas SuperH.

Processor Sales

• The 32-64 bit annual processor sales volume chart indicates ARM had most sales.

Processor Usage

• Most New Embedded Designs used 1 processor in the 2006 market survey.

Selection Issues

• Software support (OS, Compilers, Debug Tools, Applications)
• Price, Performance, Power (Battery Life (MIPS/Watt), Cooling)
• Availability and Long term availability/multiple vendors

OS Kernels in Embedded Design

• The bulk of new embedded designs use the commercial OS Kernels for real time usage.

Open Source OS

• Embedded devices are extremely cost sensitive.
• Satisfactory performance source code often needs fine tuning.

Open Source Cons

• The "Free" OS increases product development cost via device drivers & labor
• It may require more licenses and require you to publish your device's source code

Commercial Operating Systems

• Commercial Operating Systems use are dominated by Microsoft Emb. and Wind River.

Languages

• C and C++ are the main languages used in embedded Design.

What the Future Holds

• Use of multi-core processors will increase but present operating systems don't use this effectively
• Support of Wireless and mobile Internet.
• Power minimization.

Research Group Aim

• Scientific Innovation Research Group (SIRG) aims to evaluate the IOT performance and propose a secure architecture for the IoT security issues for Education.