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====== Ch5.7 Reduce Hit-Rate (四種) ======
※ (方法1) Small and Simple Caches :
1. A time-consuming portion of a cache hit is using the index portion of the address to read the tag memory and then compare it to the address. - smaller hardware is faster - keep the cache simple
2. main benefit of direct-mapped caches:the designer can overlap the tag check with the transition of the data.
※(方法2) Avoiding Address Translation During Indexing of the Cache :
1. Using virtual addresses for the cache, since hits are much more common than misses.
2. Why doesn’t everyone build virtually addressed caches ?
- One reason is protection
- another reason is that every time a process is switched the virtual addresses refer to different physical addresses, requiring the cache to be flushed.
※ (方法3) Pipelined Cache Access :
※ (方法4) Trace Caches :
- Instead of limiting the instructions in a static cache block to spatial locality, a trace cache finds a dynamic sequence of instructions including taken branches to load into a cache block.
- It comes from the cache blocks containing dynamic traces of the executed instructions as determined by the CPU transfer than containing static sequences of instructions as determined by memory.
綜合分析： + 表示改進，– 表示負面影響。
Figure 5.26 ... from
Computer Architecture : A Quantitative Approach
1. A time-consuming portion of a cache hit is using the index portion of the address to read the tag memory and then compare it to the address. - smaller hardware is faster - keep the cache simple
2. main benefit of direct-mapped caches:the designer can overlap the tag check with the transition of the data.
※(方法2) Avoiding Address Translation During Indexing of the Cache :
1. Using virtual addresses for the cache, since hits are much more common than misses.
2. Why doesn’t everyone build virtually addressed caches ?
- One reason is protection
- another reason is that every time a process is switched the virtual addresses refer to different physical addresses, requiring the cache to be flushed.
※ (方法3) Pipelined Cache Access :
※ (方法4) Trace Caches :
- Instead of limiting the instructions in a static cache block to spatial locality, a trace cache finds a dynamic sequence of instructions including taken branches to load into a cache block.
- It comes from the cache blocks containing dynamic traces of the executed instructions as determined by the CPU transfer than containing static sequences of instructions as determined by memory.
綜合分析： + 表示改進，– 表示負面影響。
Figure 5.26 ... from
Computer Architecture : A Quantitative Approach
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