[ 本帖最後由 max965 於 2009-9-5 08:04 編輯 ]

提示: 作者被禁止或刪除 內容自動屏蔽


回覆 2# 的帖子

Cache, the pronounciation is like 'cash', but, cache, follow me to spell it!

Cache is a kind of fast buffer memory.  In some old IBM papers, cache was called that way.  The necessity of cache is due to the 80:20 rule in computer memory access, you access 20% data 80% of time, so, if you store that 20% data in a faster memory, you gain a lot in speed.  Usually, cache is very expensive to build, so you cannot afford to have a big cache.  You use cache replacement policy to select the highest accessed data to be stored in cache.

Usually, the 80:20 rule is still valid in cache, so, in order to gain an even higher speed, you build a higher level cache, say L1 cache, to store that 20% data in L2.  Actually, you can play that game many times, so, nowadays, some very sophisticated CPU has L1/L2/L3 cache.

My 2 cents.

Stephen Wong @ Hong Kong


how about L3 cache