CSC 456 Fall 2013/1c wa

Trends in cache size and organization

Task 1c. Trends in cache size and organization Over the years, caches have grown larger--up to a point, and then L1 caches tended for awhile to decrease in size. Why? In the early 1980s, associativity increased; beginning about 1990, it decreased, and then by about 2000, it was increasing again. Why? When was the first machine with an L2 cache? An L3 cache? How fast were the various levels of caches, and how did this speed compare to main memory? There is a wealth of information to bring to bear on this topic.

Theory: Cache Associativity decreased as cache size became larger because it became too expensive to have to search the cache each time once the cache was too large.

The Pentium/Pentium (1995)pro was the first processor to have the l2 cache on the processor chip. Before this, the l2 cache was an option to add on to the motherboard. [1]

Systems to consider in table

Pentium amd Mips sun-microsystems: sparc ibm: power pc DEC: alpha

Penalty <100 when before 2000 after 2000 started to increase to get to main memory < 20 1 level fine <=100 2 level >=200 3 level

miss rate reported, spec benchmarks

L2 cache

System	Year	Size (cache)	Cache Speed (cc)	Main Mem Penalty (cycles)	On Chip?	Associtivity
Alpha 21164(DEC)	01/1995	96 Kb	2	?	Yes	3 way set

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References Ref1 Intel Processors First on-board L1