Multilevel caching is an important technique to overcome the limited amount of space that a first level cache can provide while still maintaining its speed. Consider a 2GHz processor with the following parameters:

Base CPI, No memory stalls	Main Memory Access Time	First Level cache Miss Rate	Second Level Direct Mapped Cache Speed	Global Miss Rate Second Level Direct Mapped Cache	Second Level Direct 8-Way Associative Cache Speed	Global Miss Rate Second Level 8-Way Associative Cache
1.5	100 ns	7%	12 cycles	3.5%	28 cycles	1.5%

A. Calculate the CPI for the processor in the table using the following three options: only a first level cache, a second level direct-mapped cache, a second level 8-way set associative cache.

Compare the three designs and explain which one provides better performance and why.

B. It is possible to have an even greater cache hierarchy than two levels. Given the processor above with a second level, direct-mapped cache, a designer wants to add a third level cache that takes 50 cycles to access and will reduce the global miss rate to 1.3%. Would this provide better performance? In general, what are the advantages and disadvantages of adding a third level cache?