buzzword
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buzzword [2015/02/04 19:23] rachata |
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| * What are not a part of the ISA? (what goes inside: uArch techniques) | * What are not a part of the ISA? (what goes inside: uArch techniques) | ||
| * Things that are not suppose to be visible to the programmer/software but typically make the processor faster and/or consumes less power and/or less complex | * Things that are not suppose to be visible to the programmer/software but typically make the processor faster and/or consumes less power and/or less complex | ||
| + | |||
| + | ===== Lecture 3 (1/17 Fri.) ===== | ||
| + | |||
| + | * Microarchitecture | ||
| + | * Three major tradeoffs of computer architecture | ||
| + | * Macro-architecture | ||
| + | * LC-3b ISA | ||
| + | * Unused instructions | ||
| + | * Bit steering | ||
| + | * Instruction processing style | ||
| + | * 0,1,2,3 address machines | ||
| + | * Stack machine | ||
| + | * Accumulator machine | ||
| + | * 2-operand machine | ||
| + | * 3-operand machine | ||
| + | * Tradeoffs between 0,1,2,3 address machines | ||
| + | * Postfix notation | ||
| + | * Instructions/Opcode/Operade specifiers (i.e. addressing modes) | ||
| + | * Simply vs. complex data type (and their tradeoffs) | ||
| + | * Semantic gap and level | ||
| + | * Translation layer | ||
| + | * Addressability | ||
| + | * Byte/bit addressable machines | ||
| + | * Virtual memory | ||
| + | * Big/little endian | ||
| + | * Benefits of having registers (data locality) | ||
| + | * Programmer visible (Architectural) state | ||
| + | * Programmers can access this directly | ||
| + | * What are the benefits? | ||
| + | * Microarchitectural state | ||
| + | * Programmers cannot access this directly | ||
| + | * Evolution of registers (from accumulators to registers) | ||
| + | * Different types of instructions | ||
| + | * Control instructions | ||
| + | * Data instructions | ||
| + | * Operation instructions | ||
| + | * Addressing modes | ||
| + | * Tradeoffs (complexity, flexibility, etc.) | ||
| + | * Orthogonal ISA | ||
| + | * Addressing modes that are orthogonal to instruction types | ||
| + | * I/O devices | ||
| + | * Vectored vs. non-vectored interrupts | ||
| + | * Complex vs. simple instructions | ||
| + | * Tradeoffs | ||
| + | * RISC vs. CISC | ||
| + | * Tradeoff | ||
| + | * Backward compatibility | ||
| + | * Performance | ||
| + | * Optimization opportunity | ||
| + | * Translation | ||
| + | |||
| + | ===== Lecture 4 (1/21 Wed.) ===== | ||
| + | |||
| + | * Fixed vs. variable length instruction | ||
| + | * Huffman encoding | ||
| + | * Uniform vs. non-uniform decode | ||
| + | * Registers | ||
| + | * Tradeoffs between number of registers | ||
| + | * Alignments | ||
| + | * How does MIPS load words across alignment the boundary | ||
| + | |||
| + | ===== Lecture 5 (1/26 Mon.) ===== | ||
| + | |||
| + | * Tradeoffs in ISA: Instruction length | ||
| + | * Uniform vs. non-uniform | ||
| + | * Design point/Use cases | ||
| + | * What dictates the design point? | ||
| + | * Architectural states | ||
| + | * uArch | ||
| + | * How to implement the ISA in the uArch | ||
| + | * Different stages in the uArch | ||
| + | * Clock cycles | ||
| + | * Multi-cycle machine | ||
| + | * Datapath and control logic | ||
| + | * Control signals | ||
| + | * Execution time of instructions/program | ||
| + | * Metrics and what do they means | ||
| + | * Instruction processing | ||
| + | * Fetch | ||
| + | * Decode | ||
| + | * Execute | ||
| + | * Memory fetch | ||
| + | * Writeback | ||
| + | * Encoding and semantics | ||
| + | * Different types of instructions (I-type, R-type, etc.) | ||
| + | * Control flow instructions | ||
| + | * Non-control flow instructions | ||
| + | * Delayed slot/Delayed branch | ||
| + | * Single cycle control logic | ||
| + | * Lockstep | ||
| + | * Critical path analysis | ||
| + | * Critical path of a single cycle processor | ||
| + | * What is in the control signals? | ||
| + | * Combinational logic & Sequential logic | ||
| + | * Control store | ||
| + | * Tradeoffs of a single cycle uarch | ||
| + | * Design principles | ||
| + | * Common case design | ||
| + | * Critical path design | ||
| + | * Balanced designs | ||
| + | * Dynamic power/Static power | ||
| + | * Increases in power due to frequency | ||
| + | |||
| + | ===== Lecture 6 (1/28 Mon.) ===== | ||
| + | |||
| + | * Design principles | ||
| + | * Common case design | ||
| + | * Critical path design | ||
| + | * Balanced designs | ||
| + | * Multi cycle design | ||
| + | * Microcoded/Microprogrammed machines | ||
| + | * States | ||
| + | * Translation from one state to another | ||
| + | * Microinstructions | ||
| + | * Microsequencing | ||
| + | * Control store - Product control signals | ||
| + | * Microsequencer | ||
| + | * Control signal | ||
| + | * What do they have to control? | ||
| + | * Instruction processing cycle | ||
| + | * Latch signals | ||
| + | * State machine | ||
| + | * State variables | ||
| + | * Condition code | ||
| + | * Steering bits | ||
| + | * Branch enable logic | ||
| + | * Difference between gating and loading? (write enable vs. driving the bus) | ||
| + | * Memory mapped I/O | ||
| + | * Hardwired logic | ||
| + | * What control signals come from hardwired logic? | ||
| + | * Variable latency memory | ||
| + | * Handling interrupts | ||
| + | * Difference betwen interrupts and exceptions | ||
| + | * Emulator (i.e. uCode allots minimal datapath to emulate the ISA) | ||
| + | * Updating machine behavior | ||
| + | * Horizontal microcode | ||
| + | * Vertical microcode | ||
| + | * Primitives | ||
| + | | ||
| + | ===== Lecture 7 (1/30 Fri.) ===== | ||
| + | |||
| + | * Emulator (i.e. uCode allots minimal datapath to emulate the ISA) | ||
| + | * Updating machine behavior | ||
| + | * Horizontal microcode | ||
| + | * Vertical microcode | ||
| + | * Primitives | ||
| + | * nanocode and millicode | ||
| + | * what are the differences between nano/milli/microcode | ||
| + | * microprogrammed vs. hardwire control | ||
| + | * Pipelining | ||
| + | * Limitations of the multi-programmed design | ||
| + | * Idle resources | ||
| + | * Throughput of a pipelined design | ||
| + | * What dictacts the throughput of a pipelined design? | ||
| + | * Latency of the pipelined design | ||
| + | * Dependency | ||
| + | * Overhead of pipelining | ||
| + | * Latch cost? | ||
| + | * Data forwarding/bypassing | ||
| + | * What are the ideal pipeline? | ||
| + | * External fragmentation | ||
| + | * Issues in pipeline designs | ||
| + | * Stalling | ||
| + | * Dependency (Hazard) | ||
| + | * Flow dependence | ||
| + | * Output dependence | ||
| + | * Anti dependence | ||
| + | * How to handle them? | ||
| + | * Resource contention | ||
| + | * Keeping the pipeline full | ||
| + | * Handling exception/interrupts | ||
| + | * Pipeline flush | ||
| + | * Speculation | ||
| + | | ||
| + | ===== Lecture 8 (2/2 Mon.) ===== | ||
| + | |||
| + | * Interlocking | ||
| + | * Multipath execution | ||
| + | * Fine grain multithreading | ||
| + | * No-op (Bubbles in the pipeline) | ||
| + | * Valid bits in the instructions | ||
| + | * Branch prediction | ||
| + | * Different types of data dependence | ||
| + | * Pipeline stalls | ||
| + | * bubbles | ||
| + | * How to handle stalls | ||
| + | * Stall conditions | ||
| + | * Stall signals | ||
| + | * Dependences | ||
| + | * Distant between dependences | ||
| + | * Data forwarding/bypassing | ||
| + | * Maintaining the correct dataflow | ||
| + | * Different ways to design data forwarding path/logic | ||
| + | * Different techniques to handle interlockings | ||
| + | * SW based | ||
| + | * HW based | ||
| + | * Profiling | ||
| + | * Static profiling | ||
| + | * Helps from the software (compiler) | ||
| + | * Superblock optimization | ||
| + | * Analyzing basic blocks | ||
| + | * How to deal with branches? | ||
| + | * Branch prediction | ||
| + | * Delayed branching (branch delay slot) | ||
| + | * Forward control flow/backward control flow | ||
| + | * Branch prediction accuracy | ||
| + | * Profile guided code positioning | ||
| + | * Based on the profile info. position the code based on it | ||
| + | * Try to make the next sequential instruction be the next inst. to be executed | ||
| + | * Predicate combining (combine predicate for a branch instruction) | ||
| + | * Predicated execution (control dependence becomes data dependence) | ||
| + | | ||
| + | | ||
| + | ===== Lecture 9 (2/4 Wed.) ===== | ||
| + | | ||
| + | * Predicate combining (combine predicate for a branch instruction) | ||
| + | * Predicated execution (control dependence becomes data dependence) | ||
| + | * Definition of basic blocks | ||
| + | * Control flow graph | ||
| + | * Delayed branching | ||
| + | * benefit? | ||
| + | * What does it eliminates? | ||
| + | * downside? | ||
| + | * Delayed branching in SPARC (with squashing) | ||
| + | * Backward compatibility with the delayed slot | ||
| + | * What should be filled in the delayed slot | ||
| + | * How to ensure correctness | ||
| + | * Fine-grained multithreading | ||
| + | * fetch from different threads | ||
| + | * What are the issues (what if the program doesn't have many threads) | ||
| + | * CDC 6000 | ||
| + | * Denelcor HEP | ||
| + | * No dependency checking | ||
| + | * Inst. from different thread can fill-in the bubbles | ||
| + | * Cost? | ||
| + | * Simulteneuos multithreading | ||
| + | * Branch prediction | ||
| + | * Guess what to fetch next. | ||
| + | * Misprediction penalty | ||
| + | * Need to guess the direction and target | ||
| + | * How to perform the performance analysis? | ||
| + | * Given the branch prediction accuracy and penalty cost, how to compute a cost of a branch misprediction. | ||
| + | * Given the program/number of instructions, percent of branches, branch prediction accuracy and penalty cost, how to compute a cost coming from branch mispredictions. | ||
| + | * How many extra instructions are being fetched? | ||
| + | * What is the performance degredation? | ||
| + | * How to reduce the miss penalty? | ||
| + | * Predicting the next address (non PC+4 address) | ||
| + | * Branch target buffer (BTB) | ||
| + | * Predicting the address of the branch | ||
| + | * Global branch history - for directions | ||
| + | * Can use compiler to profile and get more info | ||
| + | * Input set dictacts the accuracy | ||
| + | * Add time to compilation | ||
| + | * Heuristics that are common and doesn't require profiling. | ||
| + | * Might be inaccurate | ||
| + | * Does not require profiling | ||
| + | * Static branch prediction | ||
| + | * Pregrammer provides pragmas, hinting the likelihood of taken/not taken branch | ||
| + | * For example, x86 has the hint bit | ||
| + | * Dynamic branch prediction | ||
| + | * Last time predictor | ||
| + | * Two bits counter based prediction | ||
| + | * One more bit for hysteresis | ||
| + | |||
buzzword.txt · Last modified: 2015/04/27 18:20 by rachata
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