Design principles, Lecture notes of Advanced Computer Architecture

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Quantitative Principles of Computer

Design

• (^) Make the Common Case Fast
  • (^) Amdahl’s Law
• (^) CPU Performance Equation
  • (^) Clock cycle time
  • (^) CPI
  • (^) Instruction Count
• (^) Principles of Locality
• (^) Take advantage of Parallelism

CPU Performance Equation

CPU time = Seconds = Instructions x Cycles x Seconds Program Program Instruction Cycle CPU time = Seconds = Instructions x Cycles x Seconds Program Program Instruction Cycle Inst Count CPI Clock Rate Program X Compiler X (X) Inst. Set. X X Organization X X Technology X

• (^) it requires designers to be careful and pay attention to the details. Each detail might provide an opportunity for an adversary to breach the system security. Fortunately, many of the previously-encountered design principles can also guide the designer of secure systems

Information Security

• (^) Threat Classification
• (^) The design of any security system starts with identifying the threats that the system should withstand. Threats are potential security violations caused either by a planned attack by an adversary or unintended mistakes by legitimate users of the system. The designer of a secure computer system must be consider both..

• (^) 2. Unauthorized information modification: an unauthorized person can make changes in stored information or modify messages that cross a network—an adversary might engage in this behavior to sabotage the system or to trick the receiver of a message to divulge useful information or take unintended action. This kind of violation does not necessarily require that the adversary be able to see the information it has changed.

• (^) 3. Unauthorized denial of use: an adversary can prevent an authorized user from reading or modifying information, even though the adversary may not be able to read or modify the information. Causing a system “crash,” flooding a service with messages, or firing a bullet into a computer are examples of denial of use. This attack is another form of sabotage.