buzzword
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buzzword [2014/04/02 18:13] rachata |
buzzword [2014/04/07 18:17] rachata |
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| * Better/more hash function helps eliminate this | * Better/more hash function helps eliminate this | ||
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| + | ===== Lecture 26 (4/7 Mon.) ===== | ||
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| + | * Tolerate latency can be costly | ||
| + | * Instruction window is complex | ||
| + | * Benefit also diminishes | ||
| + | * Designing the buffers can be complex | ||
| + | * A simpler way to tolerate out of order is desirable | ||
| + | * Different sources that cause the core to stall in OoO | ||
| + | * Cache miss | ||
| + | * Note that stall happens if the inst. window is full | ||
| + | * Scaling instruction window size is hard | ||
| + | * It is better (less complex) to make the windows more efficient | ||
| + | * Runahead execution | ||
| + | * Try to optain MLP w/o increasing instruction windows | ||
| + | * Runahead (i.e. execute ahead) when there is a long memory instruction | ||
| + | * Long memory instruction stall processor for a while anyways, so it's better to make use out of it | ||
| + | * Execute future instruction to generate accurate prefetches | ||
| + | * Allow future data to be in the cache | ||
| + | * How to support runahead execution? | ||
| + | * Need a way to checkpoing the state when entering runahead mode | ||
| + | * How to make executing in the wrong path useful? | ||
| + | * Need runahead cache to handle load/store in Runahead mode (since they are speculative) | ||
| + | * Cost and benefit of runahead execution (slide number 27) | ||
| + | * Runahead can have inefficiency | ||
| + | * Runahead period that are useless | ||
| + | * Get rid of useless inefficient period | ||
| + | * What if there is a dependent cache miss | ||
| + | * Cannot be paralellized in a vanilla runahead | ||
| + | * Can predict the value of the dependent load | ||
| + | * How to predict the address of the load | ||
| + | * Delta value information | ||
| + | * Stride predictor | ||
| + | * AVD prediction | ||
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buzzword.txt · Last modified: 2015/04/27 18:20 by rachata
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