buzzword
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buzzword [2015/02/13 19:19] rachata |
buzzword [2015/02/18 19:22] rachata |
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| * Broadcasting tags | * Broadcasting tags | ||
| * Using dataflow | * Using dataflow | ||
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| + | ===== Lecture 13 (2/16 Mon.) ===== | ||
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| + | * OoO --> Restricted Dataflow | ||
| + | * Extracting parallelism | ||
| + | * What are the bottlenecks? | ||
| + | * Issue width | ||
| + | * Dispatch width | ||
| + | * Parallelism in the program | ||
| + | * What does it mean to be restricted data flow | ||
| + | * Still visible as a Von Neumann model | ||
| + | * Where does the efficiency come from? | ||
| + | * Size of the scheduling windors/reorder buffer. Tradeoffs? What make sense? | ||
| + | * Load/store handling | ||
| + | * Would like to schedule them out of order, but make them visible in-order | ||
| + | * When do you schedule the load/store instructions? | ||
| + | * Can we predict if load/store are dependent? | ||
| + | * This is one of the most complex structure of the load/store handling | ||
| + | * What information can be used to predict these load/store optimization? | ||
| + | * Centralized vs. distributed? What are the tradeoffs? | ||
| + | * How to handle when there is a misprediction/recovery | ||
| + | * OoO + branch prediction? | ||
| + | * Speculatively update the history register | ||
| + | * When do you update the GHR? | ||
| + | * Token dataflow arch. | ||
| + | * What are tokens? | ||
| + | * How to match tokens | ||
| + | * Tagged token dataflow arch. | ||
| + | * What are the tradeoffs? | ||
| + | * Difficulties? | ||
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| + | ===== Lecture 14 (2/18 Wed.) ===== | ||
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| + | * SISD/SIMD/MISD/MIMD | ||
| + | * Array processor | ||
| + | * Vector processor | ||
| + | * Data parallelism | ||
| + | * Where does the concurrency arise? | ||
| + | * Differences between array processor vs. vector processor | ||
| + | * VLIW | ||
| + | * Compactness of an array processor | ||
| + | * Vector operates on a vector of data (rather than a single datum (scalar)) | ||
| + | * Vector length (also applies to array processor) | ||
| + | * No dependency within a vector --> can have a deep pipeline | ||
| + | * Highly parallel (both instruction level (ILP) and memory level (MLP)) | ||
| + | * But the program needs to be very parallel | ||
| + | * Memory can be the bottleneck (due to very high MLP) | ||
| + | * What does the functional units look like? Deep pipelin and simpler control. | ||
| + | * CRAY-I is one of the examples of vector processor | ||
| + | * Memory access pattern in a vector processor | ||
| + | * How do the memory accesses benefit the memory bandwidth? | ||
| + | * Memory level parallelism | ||
| + | * Stride length vs. the number of banks | ||
| + | * stride length should be relatively prime to the number of banks | ||
| + | * Tradeoffs between row major and column major --> How can the vector processor deals with the two | ||
| + | * How to calculate the efficiency and performance of vector processors | ||
| + | * What if there are multiple memory ports? | ||
| + | * Gather/Scatter allows vector processor to be a lot more programmable (i.e. gather data for parallelism) | ||
| + | * Helps handling sparse metrices | ||
| + | * Conditional operation | ||
| + | * Structure of vector units | ||
| + | * How to automatically parallelize code through the compiler? | ||
| + | * This is a hard problem. Compiler does not know the memory address. | ||
| + | * What do we need to ensure for both vector and array processor? | ||
| + | * Sequential bottleneck | ||
| + | * Amdahl's law | ||
| + | * Intel MMX --> An example of Intel's approach to SIMD | ||
| + | * No VLEN, use OpCode to define the length | ||
| + | * Stride is one in MMX | ||
| + | * Intel SSE --> Modern version of MMX | ||
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buzzword.txt · Last modified: 2015/04/27 18:20 by rachata
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