How big should a TLB be? TLB misses are usually very fast (fewer than 10 instructions plus the cost of an exception), so it may not be worth having a huge TLB just to lower the TLB miss rate a bit. Using the SimpleScalar simulator (www.cs.wisc.edu/~mscalar/simplescalar.html) and one or more SPEC95 benchmarks, calculate the TLB miss rate and the TLB overhead (in percentage of time wasted handling TLB misses) for the following TLB configurations. Assume that each TLB miss requires 20 instructions.

a. 128 entries, two-way set associative, 4 KB to 64 KB pages (going by powers of 2).

b. 256 entries, two-way set associative, 4 KB to 64 KB pages (going by powers of 2).

c. 512 entries, two-way set associative, 4 KB to 64 KB pages (going by powers of 2).

d. 1024 entries, two-way set associative, 4 KB to 64 KB pages (going by powers of 2).

e. What would be the effect on TLB miss rate and overhead for a multitasking environment? How would the context switch frequency affect the overhead?