Dear students here we provide notes for Anna university 6TH sem Subject CS ADVANCED COMPUTER ARTCHITECTURE notes pdf. you can download. ADVANCED COMPUTER ARCHITECTURE LECTURE NOTES ANNA UNIVERSITY ADVANCED COMPUTER ARCHITECTURE LECTURE. CS ADVANCED COMPUTER ARCHITECTURE. UNIT – I. 2 Marks. is ILP .. Statically scheduled. – Dynamically scheduled (see previous lecture).
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Various types of Dependences in ILP. Touch here to read. Register renaming can be done either statically by a compiler or dynamically by the hardware. In general, there are two constraints imposed by control dependences: Whether a given dependence results in an actual hazard being detected and whether that nofes actually causes a stall are properties of the pipeline organization.
Advanced Computer Architecture(ACA) – CS – Anna university – CSE – 6th semester – question bank
For example, in the code segment: There are three different architeecture of dependences: Text from page-1 Lecture Plan Subject Code: Since a name dependence is not a true dependence, instructions involved in a name dependence can execute simultaneously or be reordered, if the name register number or memory location used in the instructions is changed so the instructions do compute conflict.
If two instructions are parallel, they can execute simultaneously in a pipeline without causing any stalls. CS Name of the subject: Here is a simple example of a loop, which adds two element arrays, that is completely parallel: Dependences are a property of programs.
The ordering between the instructions must be preserved to ensure that the value finally written corresponds to instruction j. To exploit instruction-level parallelism, determine which instructions can be executed in parallel. The original ordering must be preserved to ensure that i reads the correct value. If two instructions are dependent they are not parallel and must be executed in order. Both anti-dependences and output dependences are name dependences, as opposed to true data dependences, since there is no value being transmitted between architceture instructions.
CS Advanced Computer Architecture Lecture Notes – SEC Edition
The presence of the dependence indicates the potential for a hazard, but the actual hazard and the length of any stall is a property of the pipeline. Text from page-2 Lecture Plan Subject Code: Every instruction, except for those in the first notee block of the program, is control dependent on some set of branches, and, in general, these control dependences must be preserved to preserve program order.
The second condition simply states that one instruction is dependent on another if there exists a chain of dependences of the first type between the two instructions. For example, we cannot take an instruction css2354 the then-portion of an if-statement and move it before the ifstatement. Executing the instructions simultaneously will cause a processor with pipeline interlocks to detect a hazard and stall, thereby reducing or eliminating the overlap.
An instruction j is architectue dependent on instruction i if either of the following holds: The various techniques that are used to increase amount of parallelism are advaanced the impact of data and control hazards and increases processor ability to exploit parallelism There are two approaches to exploiting ILP. An instruction that is control dependent on a branch cannot be moved before the branch so that its execution is no longer controlled by the branch.
Add Add to Favourite Add to classroom. A control dependence determines the ordering of an instruction, i, with respect to a branch instruction so that the instruction i is executed in archtecture program order. There are two types of name dependences between an instruction i that precedes instruction j in program order: Name Dependences The name dependence occurs when two instructions use the same register or memory location, called a name, but there is no flow of data between the instructions associated with that name.
Text from page-3 Lecture Plan Subject Code: This difference is critical to understanding how instruction-level parallelism can be exploited.
Data Dependence and Hazards: Static Technique — Software Dependent 2. This dependence chain can be as long as the entire program.
Dynamic Technique — Hardware Dependent Technique Forwarding and bypassing Delayed branches and simple branch scheduling Basic dynamic scheduling scoreboarding Dynamic scheduling with renaming Dynamic branch prediction Issuing multiple instructions per cycle Speculation Dynamic memory disambiguation Loop unrolling Basic compiler pipeline scheduling Compiler dependence analysis Software pipelining, trace scheduling Compiler speculation Reduces Potential data hazard stalls Control hazard stalls Data hazard stalls from true dependences Data hazard stalls and stalls from anti dependences and output dependences Control stalls Ideal CPI Data hazard and control hazard stalls Data hazard stalls with memory Control hazard stalls Data hazard stalls Ideal CPI, data hazard stalls Ideal CPI, data hazard stalls Ideal CPI, data, control stalls 1.
Instruction-level parallelism ILP is the potential overlap the execution of instructions using ocmputer concept to improve performance of the system. Lecture Plan Subject Code: Text from ca2354 Lecture Plan Subject Code: leccture