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buzzword [2014/03/19 18:16] rachata |
buzzword [2014/03/21 18:16] rachata |
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* Approximate LRU | * Approximate LRU | ||
* Victim and next Victim policy | * Victim and next Victim policy | ||
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+ | ===== Lecture 20 (3/21 Fri.) ===== | ||
+ | |||
+ | * Set thrashing | ||
+ | * Working set is bigger than the associativity | ||
+ | * Belady's OPT | ||
+ | * Is this optimal? | ||
+ | * Complexity? | ||
+ | * Similarity between cache and page table | ||
+ | * Number of blocks vs pages | ||
+ | * Time to find the block/page to replace | ||
+ | * Handling writes | ||
+ | * Write through | ||
+ | * Need a modified bit to make sure accesses to data got the updated data | ||
+ | * Write back | ||
+ | * Simpler, no consistency issues | ||
+ | * Sectored cache | ||
+ | * Use subblock | ||
+ | * lower bandwidth | ||
+ | * more complex | ||
+ | * Instruction vs data cache | ||
+ | * Where to place instructions | ||
+ | * Unified vs. separated | ||
+ | * In the first level cache | ||
+ | * Cache access | ||
+ | * First level access | ||
+ | * Second level access | ||
+ | * When to start the second level access | ||
+ | * Performance vs. energy | ||
+ | * Address translation | ||
+ | * Homonym and Synonyms | ||
+ | * Homonym: Same VA but maps to different PA | ||
+ | * With multiple processes | ||
+ | * Synonyms: Multiple VAs map to the same PA | ||
+ | * Shared libraries, shared data, copy-on-write | ||
+ | * I/O | ||
+ | * Can these create problems when we have the cache | ||
+ | * How to eliminate these problems? | ||
+ | * Page coloring | ||
+ | * Interaction between cache and TLB | ||
+ | * Virtually indexed vs. physically indexed | ||
+ | * Virtually tagged vs. physically tagged | ||
+ | * Virtually indexed physically tagged | ||
+ | * Virtual memory in DRAM | ||
+ | * Control where data is mapped to in channel/rank/bank | ||
+ | * More parallelism | ||
+ | * Reduce interference | ||
+ |